div#bodyRight { margin: 5px 25px 25px 225px; width: 75%; }

Your two column webpage will look like

<div id="topBanner">Page Title</div>

<div id="bodyLeft">Add menu items here</div>

<div id="bodyRight">Add your content here</div>

</body>

Three column webpage with CSS

Create a file like threecol.css. Put the following code

div#bodyLeft { position: absolute; padding-left: 10px; width: 25%; }

div#bodyCenter { margin-left: 190px; margin-right: 190px; width: 50%; position: absolute; }

div#bodyRight { position: absolute; padding-right: 10px; width: 25%; right: 0%; }

div#topBanner { text-align: center; padding-bottom: 15px; }

Your three column webpage will look as follows

<div id="topBanner">Page Title</div>

<div id="bodyLeft">Add menu items here</div>

<div id="bodyCenter">Add your content here</div>

<div id="bodyRight">Add your content here</div>

Then, add your text and/or graphics to the file.

Table Less Design: Layouts with CSS

A three column webpage with CSS positioning

    
        <div id="leftnavigation"></div>
        <div id="rightnavigation"></div>
        <div id="content"></div>

The CSS should look like this:


#leftnavigation 
{
  position : absolute;
  left : 0;
  width : 150px;
  margin-left : 10px;
  margin-top : 20px;
  color : #000000;
  padding : 3px;
}

#rightnavigation 
{
  position : absolute;
  left : 80%;
  top : 20px;
  width : 140px;
  padding-left : 10px;
  z-index : 3;
  color : #000000;
  padding : 3px;
} 

#content {
  top : 0px;
  margin : 0px 25% 0 165px;
  padding : 3px;
  color : #000000;
} 


----------


More CSS Layouts:


Three Column layout with header and footer:

The CSS


html, body { margin: 0; padding: 0; }

#header { 

  width: 800px;

  float: left;

}

#maincontainer {

  width: 800px;

  float: left;

}

#nav {

  width: 200px;

  float: left;

}

#main {

  float: right;

  width: 600px;

}

#footer {

  width: 800px; 

  float: left;

}
 



The XHTML



<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<html xmlns="http://www.w3.org/1999/xhtml">

<head>

<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1" />

<title>2 Column Header and Footer Layout</title>

<link href="styles.css" rel="stylesheet" type="text/css" />

</head>



<body>

<div id="header"><h1>Header</h1></div>

<div id="maincontainer">

<div id="main">

<p>Whee</p>

<p>

</div>

<div id="nav">

<ul>

	<li><a href="">Link</a></li>

	<li><a href="">Link</a></li>

	<li><a href="">Link</a></li>

	<li><a href="">Link</a></li>

</ul>

</div>

</div>

<div id="footer"><h4>Footer</h4></div>

</body>

</html>


Web page design standards




Try to follow the following rules while creating a web-page. 


1. Decide what you want to use HTML or XHTML. Better to go 

with XHTML. Which XHTML? Strict or transitional?  Go for 

strict one, that way you will be in the most standard way.



2. If you are new into XHTML try transitional first, when you are 

comfortable in Transitional style, switch to Strict.

 Rememebr, strict will not support many non-standard tags
 
and coding you usually use, so it may sound a bit difficult.



3. Some XHTML rules


a. Simply use a Doctype.

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 
Transitional//EN"	"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
b. Use lower case for all tags

c. enclose all attribute values

d. close all tags even <hr/> <br/>

e. Try to use css for layout

f. Even assign values to empty attributes like checked='checked', readonly='true'

g. nest attributes correctly



4. Page Layout


Most recent and most standard way is to use pure css (div,span tags) to create page layouts

However, not all browsers are that advanced. With css layout horizontal alignment is problemetic. 

Also, placing page footers in the right place becomes difficult.



A good way is, try css first. If you face problems use tables for the outer layout and for internal layout (under the table) never use tables just use css(div). 
Use table internally only to display tabular data not for layout.




5. Always use both id and name tags. use id tag before name tag. 


6. For javascript use Use the Document.getElementById DOM that is compatible in all browsers


7. Always use attributes or set properties in div tag not in the td tag when you use div inside td. But use valign on the td, it does not work with div




Page layout with minimal use of table



<table>
	<tr>
		<td colspan="2">
			<div class="header">
			Header
			</div>
		</td>
	</tr>
	<tr>
		<td>
			<div class="navigation">
			Navigation
			</div>
		</td>
		<td>
			<div class="content">
			Content
			</div>
		</td>
	</tr>
	<tr>
		<td colspan="2" style="vertical-align: bottom">
			<div class="footer">
			Footer
			</div>
		</td>
	</tr>
</table>



8. <center> is deprecated and centering a block in css is difficult. So rather use the following css






div.container {

text-align: center;

}



div.text {

margin-left: auto;

margin-right: auto;

text-align: left; /* overrule inheritance */


}











What you really need to learn in Javascript?


What you really need to learn in Javascript? 


1. Where you can place JavaScript codes? 


2. Some basic programming: 


<script language="javascript" type="text/javascript">

</script> 



<script language="javascript" type="text/javascript"> 

	document.write('<b>Hello World</b>'); 

</script> 


This will only be displayed in javascript enabled browsers.


<script language="javascript" type="text/javascript"> 

	document.write('<a href="script.htm">Page Requiring Javascript</a>'); 

</script> 


3. Variables and their scopes 


<script language="javascript" type="text/javascript"> 

	var hello = 'Hello World'; 

	document.write(hello);

</script> 



var mynum = 5; 


var smokes = false; 



var riches = null; 


var today = new Date;
 

Example use of variables: 


<script language="javascript" type="text/javascript"> 

	var questions = '<p>If you have any questions about this 

 	please <a href="mailto:me@myaddress.com">email me</a>.</p>'; 

	document.write(questions);

</script> 


Another block can refer to questions variables without reassigning the value


<script language="javascript" type="text/javascript"> 

	document.write(questions);

</script> 



variables declared within a function is recognized only withing that function. Variables declared outside of a 
function is recognized anywhere in the webpage within javascript code from the declaration place. 



4. Operators 


Assignment operators 


<script language="javascript" type="text/javascript"> 

	var rich = 5000; 

	var lotsOfMoney = 100000; 

	rich = lotsOfMoney; 

	document.write(rich);

</script> 


Arithmetic and concatenation operators 


five = two + three; 

profit = income - expenses; 

income = sales * price;

payment = total / instalments; 

option = randnum % choices; 

b = ++a;

c = a++;

d = --a;

e = a--; 



Combination of Operators like c/c++ 


joy += happiness; 

price -= discount; 

capital *= interest; 

pie /= slices;

options %= choice; 


Example use:



<script language="javascript" type="text/javascript"> 

	var singlePrice = 8;

	var bulkPrice = singlePrice * 9;

	document.write('<p>Buy our Widgets $'

	+singlePrice+' for one, $'+bulkPrice+' for ten</p>'); 

</script> 




5. Comparing Variables, Logical statements 


<script language="javascript" type="text/javascript"> 

	var red = 5;

	var blue = 3;

	var match = null;

	if (red == blue) 

	{

		match = 'equal'; 

	} 

	else 

	{

		match = 'unequal'; 

	}

	document.write(red + ' and ' + blue + ' are ' + match); 

</script> 



Other comparison operators: 


if (red > blue)

if (red >= blue)

if (red < blue)

if (red <= blue)

if (red != blue) 




Combining more than one comparison 


if ((red == blue) || (red == green)) 



<script language="javascript" type="text/javascript"> 

	var red = 5;

	var blue = 3;

	var green = 3;

	var match = null;

	
	if ((red == blue) && (red == green)) 

	{

		match = 'equal';

	} 

	else 

	{

		purple = 'unequal';

	}

	document.write(red + ' and ' + blue + ' are ' + match);

</script> 



Comparison in short


red == blue ? match = 'equal' : match = 'unequal'; 



instead of


if (red == blue) 

{

	match = 'equal';

} 

else 

{

      match = 'unequal'; 

}



Example Use:



<script language="javascript" type="text/javascript">

	var discPrice = 25;

	var regPrice = 25;

	var discount = regPrice - discPrice;

	if (discount > 0)

		document.write('<p>Save $'+discount+ ' off the normal price of $' +regPrice+ 'now only $'+discPrice+'.</p>');

	else

		document.write('<p>Buy now at our regular cheap price of $' + regPrice+'.</p>' ); 

</script>



6. Switch statement in Javascript, very similar to C/C++/Java


use switch instead of multiple if/else if


<script language="javascript" type="text/javascript">

	var red = 1;

	var result = null;

	switch (red) 

	{

		case 1: result = 'one'; break; 

		case 2: result = 'two'; break;

		default: result = 'unknown';

	}

	document.write(result);

</script> 



Example:


<script language="javascript" type="text/javascript"> 

	var message = 0;

	switch (message) 

	{

		case 1: document.write('Merry Christmas'); break;

		case 2: document.write('Happy New Year'); break; 

		case 3: document.write('Happy Easter'); break;

		case 4: document.write('Happy Holidays'); break;

		default: document.write('Welcome');

	}

</script> 



7. Function 

	
	
Defining a function 


function myCode() 

{

	document.write('<b>Hello World</b>'); 

} 


calling a function


myCode()


Example:


function displayMessage() 

{

	switch (message) 

	{

		case 1: document.write('Merry Christmas'); break;

		case 2: document.write('Happy New Year'); break;

		case 3: document.write('Happy Easter'); break;

		case 4: document.write('Happy Holidays'); break;

		default: document.write('Welcome');

	}

}	 



var message = 0;

displayMessage(); 



parameter passing


function writeSentence(argument1,argument2) 

{

	document.write('The '+argument1+' is '+argument2+'.<br />'); 

} 




var a = 'table';

var b = 'chair';

var c = 'red';

var d = 'blue';

writeSentence(a,c);

writeSentence(b,c);

b = 'other ' + b;

writeSentence(b,d); 

writeSentence('table',b); //passing the value directly


Example:


function displayMessage(m) 

{

	switch (m) 

	{

		case 1: document.write('Merry Christmas'); break;

		case 2: document.write('Happy New Year'); break;

		case 3: document.write('Happy Easter'); break;

		case 4: document.write('Happy Holidays'); break;

		default: document.write('Welcome');

	}

} 



In Javascript functions can also return values 


function validField(fld) 

{

	if (fld == '') return false; 

	return true;

} 



function validField(fld) 

{

	return (fld != '');

} 


How to receive returned values and process 

document.write(myField + ' is ');

if (!validField(myField)) 

{

	document.write('not '); 

}

document.write('empty'); 


8. Alert and confirm 


	
alert('Alert Message');  


Will display a message box with the message. Very useful in debugging javascript applications. 


use confirm(), when you need user agreement on an issue. like: 


if (confirm('Select a button'))

{

	alert('You selected OK'); 

}

else 

{

	alert('You selected Cancel'); 

}



9. comments 



// Scrolling Ad Javascript

// copyright 3rd September 2004, by Stephen Chapman 

// permission to use this Javascript on your web page is 

// granted provided that all of the code in this script (including 

// these comments) is used without any alteration 



or



/* Scrolling Ad Javascript

copyright 3rd September 2004, by Stephen Chapman

permission to use this Javascript on your web page is

granted provided that all of the code in this script (including

these comments) is used without any alteration */ 




10. Debugging JavaScript


    Test in different browsers like IE, Mozilla, Firfox, Netscape 

    Enable Javascript and script debugging

    Script debugging usually reside under tools menu under browsing or web development sub-options


    
    
    Using alert to check variable values or if you can reach to a particular point of your code

    
    use bookmarklets, these are small scripts that can be used as plug in into browsers to provide error information.

    
    
    Use firebug in firefox, also use error console under tools menu to debug javascript error.

    
    Visual interdev provides Javascript debugging you may also enable external debugging by such programs

    
    
11. External javascript



You can place all of your javascript codes to an external file. and use the file scripts/functions from any webpage. 

You just need to provide a reference to that external file.


You can provide reference as follows:


<script language="javascript" type="text/javascript" 

	src="hello.js">

</script> 


Note:  do not include any <script> or </script> in the external file. 



12.  Using <noscript> tag:  this tag may help you to provide some information to the visitors  

when javascript is disabled or not supported by the browsers.



<script language="javascript" type="text/javascript">

	document.write('<b>Hello Javascript World</b>'); 

</script>


<noscript>Hello World Without Javascript</noscript> 


<noscript>

	This page uses Javascript. Your browser either

	doesn't support Javascript or you have it turned off.

	To see this page as it is meant to appear please use

	a Javascript enabled browser.

</noscript>



13. Objects and properties in Javascript 


var strlen = myField.length; 

var str = mynum.toString(); 


function theLetter(num) 

{

	var str = 'abcdefghijklmnopqustuvwxyz';

	return str.substr(num-1,1);

}


document.write(theLetter(5)); 



14. Arrays in Javascript 


var myArray = new Array(); 


var myArray = new Array('message one',

'message two','message three'); 

document.write(myArray[0]); 

myArray[3] = 'message four'; 



function displayMessage(m) 

{

	var greeting = new Array('Welcome','Merry Christmas',

	'Happy New Year','Happy Easter','Happy Holidays');

	if (m < 0 || m > greeting.length) m = 0;

	document.write(greeting[m]); 


} 


15. Loops


for (var i=0; i<10; i++) 

{

	document.write(i);

} 



var x = 0;

while (x<10) 

{

	document.write(x); 

	x++;

} 


var x = 12;

do 

{

	document.write(x); 

	x++;

} while (x<10) 



16. Date and Time in Javascript


//current date

var myDate = new Date; 



myDate.setDate(15);

myDate.setMonth(3); // January = 0

myDate.setFullYear(2006); 


myDate.setDate(myDate.getDate()+7); 




How to implement multiple tab webpages in Ajax and Javascript


The following two examples will demonstrate how to use javascript and/or ajax to implement multiple tab webpages.

http://www.dynamicdrive.com/dynamicindex17/ajaxtabscontent/ 



http://www.barelyfitz.com/projects/tabber/example2.html



I hope to be familiar with these concepts and use them in my work soon.



Handling Checkbox arrays with Javascript::GetElementsByName:XHTML supported


The following code demonstrates how to handle checkboxes with javascript. Note the names of all check boxes are same myInput[]. It could also be myInput. Both works as an array to contain the controls' values. I prefer myInput[] as you can handle this control in PHP as an array. If you use $arr=$_POST['myInput'], $arr will contain the values of the controls.  


Note the use of getElementsByName(). It is easy to manipulate javascript controls using this name. You do not need to send a value/control to the function. And in many times, document.myform.control, does not work right, specially if you want to main XHTML standard[i need to check more on this]. getElementById is also very useful. You may use getElementById for most times, but with checkbox arrays getElementsByName is better choice. 



Also, note that when a form is submitted only the values of the checked check boxes are submitted to the server. You may wish to use hidden controls to keep the values, so that all values are submitted and  based on the checked/non-checked you can ..control your work 



<html>
	<head>
		<script type="text/javascript">
			function getElements()
			  {
			  var x=document.getElementsByName("myInput[]");
			  alert(x.length);
			  alert(x[0].value);
			  alert(x[1].value);
			  alert(x[2].value);


			  }
		</script>
</head>

<body>
	<input name="myInput[]" type="checkbox" size="20" value='10'/>10 

	<input name="myInput[]" type="checkbox" size="20" value='20' />20

	<input name="myInput[]" type="checkbox" size="20" value='30' />30

	





Want to check how the code works, check below 







10

20

30







Javascript by Example


Java Script by Example:


Please check the URL:


http://examples.oreilly.com/jscript2/

Javascript - Form validation



The code will be helpful in validating data entry forms such as: user registration, user creation. validate_required is used by all other functions


function validate_required(field,alerttxt)
	{
		with (field)
		{
			if (value==null||value=='')
			{
				alert(alerttxt);return false
			}
			else {return true}
		}
	}
	
	function validateTicketCreateForm(thisform)
	{
		with (thisform)
		{
			if (validate_required(type,'Type must be filled out!')==false)
			{type.focus();return false}
			
			if (validate_required(subject,'Subject must be filled out!')==false)
			{subject.focus();return false}
						
		}
	}

	function validate_customer_create_form(thisform)
	{
		with (thisform)
		{
			if (validate_required(firstName,'First name must be filled out!')==false)
			{firstName.focus();return false}
			
			if (validate_required(lastName,'Last name must be filled out!')==false)
			{lastName.focus();return false}
			
			if (validate_required(phone,'Phone must be filled out!')==false)
			{phone.focus();return false}
			
		}
	}
	
	
	function validateUserCreateForm(thisform)
	{
		with (thisform)
		{
						
			if (validate_required(firstName,'First name must be filled out!')==false)
			{firstName.focus();return false}
			
			if (validate_required(lastName,'Last name must be filled out!')==false)
			{lastName.focus();return false}
			
			if (validate_required(shortName,'Short name must be filled out!')==false)
			{shortName.focus();return false}
			
			if (validate_required(username,'Username must be filled out!')==false)
			{username.focus();return false}
			
			
			if (validate_required(password,'Password must be filled out!')==false)
			{password.focus();return false}
			
			if (password.value.length < passwordLength.value) {alert("Password must be at least "+ passwordLength.value +" char long");	password.focus();return false}
			
			if (validate_required(password2,'Please re-enter password!')==false)
			{password2.focus();return false}
			
			if (password.value != password2.value)
			{
				alert("Password did not match");
				password2.focus();
				return false			
			}
			
			
		}
	}



JavaScript - Miscellaneous Validations



	function validateDomainName(strValue) 
	{
		return /www\.[a-z0-9_\-]+\.[a-z]{2, 3}/ig.test(strValue);		
	}

	function validateDomainName(strValue) 
	{
		return /www\.[a-z0-9_\-]+\.[a-z]{2, 3}/ig.test(strValue);		
	}


	//not 100% right, will fix later
	function checkDateFormat()
	{
		var pattern = new RegExp(0|1[0-9]/[0-3][0-9]/[0-9][0-9]);
		if(document.getElementById('timestampStarted').value.match(pattern))
		{
			var date_array = document.getElementById('timestampStarted').value.split('/');
			
			var month = date_array[0];
			var day = date_array[1];
			var year = date_array[2];

			// This instruction will create a date object
			source_date = new Date(year,month,day);
	
			if(month != source_date.getMonth())
			{
				alert('Month is not valid!');
				return false;
			}
	
			if(day != source_date.getDate())
			{
				alert('Day is not valid!');
				return false;
			}
			
			if(year != source_date.getYear())
			{
				alert('Year is not valid!');
				return false;
			}
		}
		else
		{
			alert('Date format is not valid!');
			return false;
		}
	
		return true;
	}



	function validateEmail( strValue) 
	{
		var objRegExp  = /(^[a-z]([a-z_\.]*)@([a-z_\.]*)([.][a-z]{3})$)|(^[a-z]([a-z_\.]*)@([a-z_\.]*)(\.[a-z]{3})(\.[a-z]{2})*$)/i;

  		//check for valid email
  		return objRegExp.test(strValue);
	}


//AJAX Example
function ajaxFunctionGeneral()
	{
		var page_request = false

		if (window.XMLHttpRequest) // if Mozilla, IE7, Safari etc
			page_request = new XMLHttpRequest()
		else if (window.ActiveXObject)
		{ // if IE
			try 
			{
				page_request = new ActiveXObject("Msxml2.XMLHTTP")
			} 
			catch (e)
			{
				try
				{
					page_request = new ActiveXObject("Microsoft.XMLHTTP")
				}
				catch (e)
				{
				}
			}
		}
		else		
			return false
		return page_request;
	}

	function reboot(deviceId)
	{
		var response=confirm('Are you sure to reboot');
		
		if(!response)
			exit;
		
		page_request = ajaxFunctionGeneral();
		if (!page_request) return false;
		
		page_request.onreadystatechange=function()
      {
      	if(page_request.readyState==4)
        	{
        		var response=page_request.responseText;
        		var displayArea = document.getElementById('showDiagnosticsResults');
        		displayArea.value = response;
        	}
      }
		page_request.open('GET', '/Inventory/Diagnostics/reboot.php?deviceId='+deviceId, true)
		page_request.send(null)
	}




Javascript Codes



Javascript is a very powerfull scripting language for web-site development. Also, it is in much demand. In Europe Javascript experts earn 29-58 pound/hour [ref: Internet]



	var serviceInstancesArrAtLoad = Array();
	var serviceInstancesArrAtSubmit = Array();
	var tempArr=Array();	
	
	function validate_required(field,alerttxt)
	{
		with (field)
		{
			if (value==null||value=='')
			{
				alert(alerttxt);return false
			}
			else {return true}
		}
	}
	
	function validateTicketCreateForm(thisform)
	{
		with (thisform)
		{
			if (validate_required(type,'Type must be filled out!')==false)
			{type.focus();return false}
			
			if (validate_required(subject,'Subject must be filled out!')==false)
			{subject.focus();return false}
						
		}
	}

	function validate_customer_create_form(thisform)
	{
		with (thisform)
		{
			if (validate_required(firstName,'First name must be filled out!')==false)
			{firstName.focus();return false}
			
			if (validate_required(lastName,'Last name must be filled out!')==false)
			{lastName.focus();return false}
			
			if (validate_required(phone,'Phone must be filled out!')==false)
			{phone.focus();return false}
			
		}
	}
	
	
	function validateUserCreateForm(thisform)
	{
		with (thisform)
		{
						
			if (validate_required(firstName,'First name must be filled out!')==false)
			{firstName.focus();return false}
			
			if (validate_required(lastName,'Last name must be filled out!')==false)
			{lastName.focus();return false}
			
			if (validate_required(shortName,'Short name must be filled out!')==false)
			{shortName.focus();return false}
			
			if (validate_required(username,'Username must be filled out!')==false)
			{username.focus();return false}
			
			/*
			if (validate_required(password,'Password must be filled out!')==false)
			{password.focus();return false}
			
			if (password.value.length < passwordLength.value) {alert("Password must be at least "+ passwordLength.value +" char long");	password.focus();return false}
			
			if (validate_required(password2,'Please re-enter password!')==false)
			{password2.focus();return false}
			
			if (password.value != password2.value)
			{
				alert("Password did not match");
				password2.focus();
				return false			
			}
			*/
			
		}
	}

	function validate_assign_group_form(thisform)
	{
		with (thisform)
		{
			if (validate_required(groupId,'Group name must be filled out!')==false)
			{groupId.focus();return false}
			
			if (validate_required(userId,'Action on invalid user!')==false)
			{userId.focus();return false}		
		}
	}
	
	function validateGroupCreateForm(thisform)
	{
		with (thisform)
		{
			if (validate_required(name,'Group name must be filled out!')==false)
			{name.focus();return false}
			
		}
	}
	
	function validateAssignGroupPermissionForm(thisform)
	{
		with (thisform)
		{
			if (validate_required(taskId,'Task module name must be filled out!')==false)
			{taskId.focus();return false}
			
		}
	}
	
	function validateAssignTaskPermissionForm(thisform)
	{
		with (thisform)
		{
			if (validate_required(groupId,'Group name must be filled out!')==false)
			{groupId.focus();return false}
			
		}
	}
	
	function validateUserEditForm(thisform)
	{
		with (thisform)
		{
						
			if (validate_required(firstName,'First name must be filled out!')==false)
			{firstName.focus();return false}
			
			if (validate_required(lastName,'Last name must be filled out!')==false)
			{lastName.focus();return false}
			
			if (validate_required(shortName,'Short name must be filled out!')==false)
			{shortName.focus();return false}
			
			if (validate_required(username,'Login id must be filled out!')==false)
			{username.focus();return false}
						
			if (password.value.length>0)
			{
				if (password.value.length < passwordLength.value) {alert("Password must be at least "+ passwordLength.value +" char long");	password.focus();return false}
				
				if (validate_required(password2,'Please re-enter password!')==false)
				{password2.focus();return false}
			}
			
			if (password.value != password2.value)
			{
				alert("Password did not match");
				password2.focus();
				return false
			}
			
		}
	}
	
	function validateInventoryCreateForm(thisform)
	{
		with (thisform)
		{
			if (validate_required(serial,'serial must be filled out!')==false)
			{serial.focus();return false}
			
			if (validate_required(hardwareAddress,'Hardware Address must be filled out!')==false)
			{hardwareAddress.focus();return false}
		}
	}
	
	function validateInventoryTypeCreateForm(thisform)
	{
		with (thisform)
		{
			if (validate_required(name,'Name must be filled out!')==false)
			{name.focus();return false}
		}
	}
	
	function validateInventoryModelCreateForm(thisform)
	{
		with (thisform)
		{
			if (validate_required(name,'Name must be filled out!')==false)
			{name.focus();return false}
			
			if (validate_required(manufacturerId,'Manufacturer must be filled out!')==false)
			{manufacturerId.focus();return false}
			
			if (validate_required(typeId,'Type must be filled out!')==false)
			{typeId.focus();return false}
			
			
		}
	}
	
	function validateInventoryManufacturerCreateForm(thisform)
	{
		with (thisform)
		{
			if (validate_required(name,'Name must be filled out!')==false)
			{name.focus();return false}
		}
	}
	
	
	function validateServiceCreateForm(thisform)
	{
		with (thisform)
		{
			if (validate_required(name,'Name must be filled out!')==false)
			{name.focus();return false}
			
			if (validate_required(typeId,'Type must be filled out!')==false)
			{typeId.focus();return false}
			
			
		}
	}
	
	function validateHostingCreateForm(thisform)
		{
			with (thisform)
			{
				if (validate_required(serviceId,'Service must be filled out!')==false)
				{serviceId.focus();return false}
				
				if (validate_required(storageSpace,'Storage space must be filled out!')==false)
				{storageSpace.focus();return false}
			}
		}
		
	function validateDomainName(strValue) 
	{
		return /www\.[a-z0-9_\-]+\.[a-z]{2, 3}/ig.test(strValue);
		
		//var objRegExp  = /^\w+([\.-]?\w+)*(\.\w{2,3})/;

  		//check for valid domain
  		//return objRegExp.test(strValue);
	}
	
	function validateDomainServiceCreateForm(thisform)
	{
		with (thisform)
		{
			if (validate_required(name,'Domain name must be filled out!')==false)
			{name.focus();return false}
			
			/*if (validateDomainName(name.value)==false)
			{alert('Please enter valid domain name');name.focus();return false;}*/
			
			if (validate_required(registrar,'Registrar must be filled out!')==false)
			{registrar.focus();return false}
			
			if (validate_required(registrationTimestamp,'Registration timestamp must be filled out!')==false)
			{registrationTimestamp.focus();return false}
			
			if (validate_required(expiryTimestamp,'Expiry timestamp must be filled out!')==false)
			{expiryTimestamp.focus();return false}
			
			if (validate_required(username,'User name must be filled out!')==false)
			{username.focus();return false}
			
			if (validate_required(password,'Password must be filled out!')==false)
			{password.focus();return false}
			
			if (password.value.length < passwordMinLength.value || password.value.length>passwordMaxLength.value)
			{alert('Password must be '+ passwordMinLength.value+ '-'+ passwordMaxLength.value +' chars long');password.focus();return false;}
			
			if (password.value != password2.value)
			{alert('Password must match');password2.focus();return false;}
		}
	}
	
	
	
	
	function validateCommunityCreateForm(thisform)
	{
		with (thisform)
		{
			if (validate_required(name,'Name must be filled out!')==false)
			{name.focus();return false}
		}
	}
	
	function validatePostalCodeCreateForm(thisform)
	{
		with (thisform)
		{
			if (validate_required(postalCode,'Postal code must be filled out!')==false)
			{postalCode.focus();return false}
			
			if (validate_required(communityId,'Community must be filled out!')==false)
			{communityId.focus();return false}
		}
	}
	
	function validateStreetTypeCreateForm(thisform)
	{
		with (thisform)
		{
			if (validate_required(name,'Name must be filled out!')==false)
			{name.focus();return false}
		}
	}
	
	function validateStreetCreateForm(thisform)
	{
		with (thisform)
		{
			if (validate_required(name,'Name must be filled out!')==false)
			{name.focus();return false}
			
			if (validate_required(typeId,'Type must be filled out!')==false)
			{typeId.focus();return false}
			
			if (validate_required(communityId,'Community must be filled out!')==false)
			{communityId.focus();return false}
		}
	}
	
	function validateUnitCreateForm(thisform)
	{
		with (thisform)
		{
			if (validate_required(streetId,'Street must be filled out!')==false)
			{streetId.focus();return false}
			
			if (validate_required(communityId,'Community must be filled out!')==false)
			{communityId.focus();return false}
			
			if (validate_required(number,'Number must be filled out!')==false)
			{number.focus();return false}
			
			if (validate_required(nodeId,'Node must be filled out!')==false)
			{nodeId.focus();return false}
			
		}
	}
	
	function validatePlantCreateForm(thisform)
	{
		with (thisform)
		{
			if (validate_required(name,'Name must be filled out!')==false)
			{name.focus();return false}
		}
	}
	
	function validateCreateTicketCategoryForm(thisform)
	{
		with (thisform)
		{
			if (validate_required(name,'Name must be filled out!')==false)
			{name.focus();return false}
		}
	}
	
	
	function validateStartWorkOnTicketForm(thisform)
	{
		with (thisform)
		{
			if (validate_required(startTimestamp,'Start Timestamp must be filled out!')==false)
			{startTimestamp.focus();return false}
		}
	}
	
	function validateTicketReportForm(thisform)
	{
		with (thisform)
		{
			if (validate_required(date,'Date must be filled out!')==false)
			{date.focus();return false}
		}
	}
	
	
	function validateCloseTicketForm(thisform)
	{
		with (thisform)
		{
			if (validate_required(date,'Date must be filled out!')==false)
			{date.focus();return false}
			
			if (validate_required(time,'Time must be filled out!')==false)
			{time.focus();return false}
			
		}
	}

	function validateCreateWorkOrder(thisform)
	{
		with (thisform)
		{
			if (validate_required(inventoryId,'Inventory must be filled out!')==false)
			{inventoryId.focus();return false}
			
			if (validate_required(assignedTo,'Assigned to must be provided!')==false)
			{assignedTo.focus();return false}
			
			if (validate_required(scheduledDate,'Scheduled date must be provided!')==false)
			{scheduledDate.focus();return false}
			
			if (validate_required(scheduledTime,'Scheduled time must be provided!')==false)
			{scheduledTime.focus();return false}
			
		}
	}
	
	
	
	
	function addService(services,serviceId)
	{
		for (var i = 0; i < services.length; i++) 
		{
			if (services.options[i].selected) 
			{
				serviceIdLength = serviceId.length++;
				serviceId.options[serviceIdLength].text = services.options[i].text;
				serviceId.options[serviceIdLength].value = services.options[i].value;
				
			}
		}
	}
	
	
	function removeService(serviceId)
	{
		for (var i = 0; i < serviceId.length; i++) 
		{
			if (serviceId.options[i].selected) 
			{
				
				serviceId.options[i].text = '';
				serviceId.options[i].value = '';
				serviceId.options[i].selected = false;
				serviceId.options[i].remove();
			}
			
		}
		
	}
	
	function validateAssignInventoryForm()
	{
		
		var serviceArr=document.getElementsByName("serviceArr[]");
		length=serviceArr.length;
		isAnySelected = false;
		
		for (var i=0;i 0)
			   isServiceRequested = 1;
			   
			if (serviceArr[i].checked == true)
			{
			   if (inventoriesHavingSameService[service] >= 0)
			   	inventoriesHavingSameService[service]=inventoriesHavingSameService[service]+1;
			   else 
			   	inventoriesHavingSameService[service]=1;
			   
			   if (servicesHavingSameInventory[inventory] > 0)
			   	servicesHavingSameInventory[inventory]=servicesHavingSameInventory[inventory]+1;
			   else
			   	servicesHavingSameInventory[inventory]=1;
			}
			
			
		}	
		if (   (!isAnySelected) && (isServiceRequested) )
		{
			alert('Service & inventory requested. But no checkbox is selected');
			return false;
		}
		else if (!isAnySelected)
		{
			var response = confirm('No checkbox is selected, do you want to proceed');
			if (!response) return false;
		}
		
		var errMsg ='';
		
		for (k=1;k= 0 )
			{	
				if ( (serviceRequested[k] != inventoriesHavingSameService[k])  )
				{
					if (serviceRequested[k]>0) 
						errMsg = errMsg + "Inventory is not checked properly for service " + k +", Requested:" + serviceRequested[k] +", Assigned:" + inventoriesHavingSameService[k] + "\n";
					else if (serviceRequested[k]==0 && inventoriesHavingSameService[k]>0)
						errMsg = errMsg + "Inventory is not checked properly for service " + k +", Requested:" + serviceRequested[k] +", Assigned:" + inventoriesHavingSameService[k] + "\n";
				}
			}
		}
			
		if (errMsg.length>0)
		{
			alert(errMsg);
			return false;
		}
		return true;
	}
	
	//not 100% right, will fix later
	function checkDateFormat()
	{
		var pattern = new RegExp(0|1[0-9]/[0-3][0-9]/[0-9][0-9]);
		if(document.getElementById('timestampStarted').value.match(pattern))
		{
			var date_array = document.getElementById('timestampStarted').value.split('/');
			
			var month = date_array[0];
			var day = date_array[1];
			var year = date_array[2];

			// This instruction will create a date object
			source_date = new Date(year,month,day);
	
			if(month != source_date.getMonth())
			{
				alert('Month is not valid!');
				return false;
			}
	
			if(day != source_date.getDate())
			{
				alert('Day is not valid!');
				return false;
			}
			
			if(year != source_date.getYear())
			{
				alert('Year is not valid!');
				return false;
			}
		}
		else
		{
			alert('Date format is not valid!');
			return false;
		}
	
		return true;
	}

	//used by assignService.php
	function initializeServiceInstanceArr()
	{
		if (serviceInstancesArrAtLoad.length == 0)
			serviceInstancesArrAtLoad=document.getElementsByName("serviceInstances[]");
		length=serviceInstancesArrAtLoad.length;

		for(i=0;i0 )
			{
				var forwardAddresses = forwardAddress.value.split(',');
				var length=forwardAddresses.length;
				for(var i=0;i=1)
				{
					lengthModelId=modelId.options.length;
					modelId.options[lengthModelId-1]=null;
				}
      
        		for(var i=0;i=1)
				{
					lengthAddressId=addressId.options.length;
					addressId.options[lengthAddressId-1]=null;
				}
      
        		for(var i=0;i=1)
				{
					lengthServiceId=serviceId.options.length;
					serviceId.options[lengthServiceId-1]=null;
				}
      
        		for(var i=0;i passwordMaxLength.value)
			{alert('Password length should be <= '+passwordMaxLength.value );password.focus();return false}
			
						
			if (validate_required(password2,'Please re-enter site password !')==false)
			{password2.focus();return false}
			
			if (password.value != password2.value)
			{
				alert("Site User Passwords must match");
				password2.focus();
				return false
			}
		}
	}
	
	function validateHostingDomainUserCreateForm(thisform)
	{
		with (thisform)
		{
			if (validate_required(domainId,'Domain name must be filled out!')==false)
			{domainId.focus();return false}
			
			
			if (validate_required(username,'Domain user name must be filled out!')==false)
			{username.focus();return false}
			
			if (validate_required(password,'Domain password must be filled out!')==false)
			{password.focus();return false}
						
			if ( password.value.length  < passwordMinLength.value )
			{ alert('Password length should be at least '+passwordMinLength.value); password.focus();return false }
			
			if (password.value.length  > passwordMaxLength.value)
			{alert('Password length should be <= '+passwordMaxLength.value );password.focus();return false}
			
			
			if (validate_required(password2,'Please re-enter site password !')==false)
			{password2.focus();return false}
			
			if (password.value != password2.value)
			{
				alert("Domain User Passwords must match");
				password2.focus();
				return false
			}
		}
	}
	
	
	//outage
	function validateOutageCreateForm(thisform)
	{
		with (thisform)
		{
			if (validate_required(subject,'Subject must be filled out!')==false)
			{subject.focus();return false}
			
			//check community selection
			var communityNamesArr=document.getElementsByName("communityNames[]");
			lengthArr= communityNamesArr.length;			
			var isAnySelected = false;
			
			for (var i=0;i


Introduction to JQuery



 

     Introduction to JQuery
    
 JQuery Tutorials
    
 Google Ajax Libraries API

 


JavaScript Frameworks



  

     Discussion on the best JavaScript Framework
    
 Google Web Toolkit (GWT)
    
 DOJO: Home Page
    
JQuery
    
 Dojo in Wikipedia
    
 Comparison of JavaScript frameworks
    
 A Book on DOJO
    
 Install DOJO 

    
 DOJO Hello World Application 


  


GWT: Google Web Toolkit



  

     http://code.google.com/webtoolkit/overview.html

    
 GWT: Product Overview: Links to installation and implementation guides

    
 GWT: Getting Started Guide





  


JavaScript DOM: Must knowledge to understand Ajax



 

     Understanding Javascript DOM is the first step to understand Ajax.
    
 DOM provides many methods to access and edit individual components of a web-page/document. The methods are called getters.
    
  < div id = 'test' > Hello < /div > getElementById method can reference to this div element. var testDiv = document.getElementById("test"); CSS #test{} refers to the same area of the document
   
 getElementsByTagName: all the elements with the partcular tag name. Returns an array. var testTag = document.getElementsByTagName("p"); just like p{} in CSS applies to all  tags. 
   
 testTag.length can be useful.
   
 You can also cycle through the elements and take some actions
         for(var i = 0; i < testTag.length ; i++){
         //do something
      }
   
   
 Another example: document.getElementById("test").getElementsByTagName("p"); [CSS #test p{} - will affect the same area in CSS]
   
 DOM provides getAttribute () : can access the value of an attribute. < p id='test' title='justEtc Computer' > Hello <p> : var title= document.getElementById("test").getAttribute("title");
  
 Web-page can be thought of a set of interconected nodes. getElementById, getElementsByTagName, getAttribute - all help in accessing the nodes. 
  
 Three basic types of nodes in web-pages: element, text, attribute. element - building block, text = attribute = content
 Every node is contained under another node. So there will be parent and child relationships. parentNode, childNode - are corresponding methods for accessing parents and childs.
 Example: var test = document.getElementById("test"); var testParent= test.parentNode; var testChild = test.childNodes;
 
 childNodes - returns an array 
 
 var allEle = document.getElementsByTagName("*"); - a collection of all the elements of the web-page.
  
 firstChild - first Child of an element, lastChild - lastChild of an element, previousSibling, nextSibling -  having same parent of the current node (next element), nodeValue, nodeValue - content of a node,  
 
 DOM Setters
 
 Using DOM, you can create elements dynamically and put it in the document. createElement() - method serves the purpose
 
var paragraph = document.createElement("p"); - element created - element node - but not inserted in the document yet

var textNode = document.createTextNode("A new text node from DOM!"); - creates a text node


 setAttribute() - method can be used to set the attributes of a node. example: paragraph.setAttribute("title", "introduction"); 

 appendChild() - append one node under another node;
 
    var pNode = document.createElement("p");
    var textNode = document.createTextElement("How is it going?");
     pNode.setAttribute("title","Test Title");
     pNode.appendChild(textNode);     
     var testDiv = document.getElementById("testDiv");
     testDiv.appendChild(pNode);

 
 removeChild() - helps to remove a child node from a parent node
 


Ajax: An Overview



 

    Ajax: dynamically changes a portion of the current web-page without refreshing the total web-page. Resembles the way IFrame works. So far I know, google uses IFrame to display/refresh maps in web-pages
   
 XMLHttpRequest is the object that serves the purpose of Ajax 
   
 The way it works: create an instance of the XMLHttpRequest object, send request to the back-end web-page that will do some processing and perhaps return some data, receive the response data, dynamically change the content of the target area, you may need to get a reference to the target area using DOM, after sending request - you have to wait for the response to come back
 create an instance of the XMLHttpRequest object: It varies for the different browsers. IE provides ActiveX Control for the purpose. A sample code can be as follows:


  function getAjaxObject(){
    var ajaxObject = false;
    if (window.XMLHttpRequest){
         ajaxObject = new XMLHttpRequest();
    }else if (window.ActiveXObject) {
      try{
        ajaxObject = new ActiveXObject("Msxml2.XMLHTTP");
      }catch(e){
         try{
          ajaxObject = new ActiveXObject("Microsoft.XMLHTTP");
         }catch(e){
           ajaxObject = false;
         }

      }
    }
    return ajaxObject; 
  }


 XMLHttpRequest has three core components. onreadystatechange - event to notify response has come or identify server activity, open - method , send method

 use of onreadystatechange 
if (ajaxObject){
   ajaxObject.onreadystatechange = takeAction; //takeAction - reference to a function
}


 Open method specifies the server side script to handle the request, data to send to the server, method of sending (GET, POST) : Required: type of request (first argument), location of the file in the server (2nd argument) 

 Open method: third argument: true = processing will be done asynchronously, false = synchronous processing - browser will stop processing until response comes [true is usually better]

 send : send method initiates the request : also passes data to the server 
 For GET method the argument can be set to null, for POSt method the argument can be a query string such as "id=500&name=keith&age=18"
 use setRequestHeader() - to provide metadata 
 Sample code:
 var ajaxObject = getAjaxObject();
 if (ajaxObject ){
    ajaxObject.onreadystatechange = takeAction; 
    ajaxObject.open("POST","file.jsp", true);
    ajaxObject.setRequestHeader("Content-type", "application/x-www-form-urlencoded");
    ajaxObject.send("id=500&name=keith&age=18");
 }

 How to receive and process the response:
 The readyState property indicates the current status of the request. 0 - Uninitialized, 1 - Loading, 2 - Loaded, 3 - interactive, 4 - complete
 each time the value of readyState changes onreadystatechange - event is triggered. At value 4, we can collect the response and change the web-page dynamically
 Sample:
 function takeAction(ajaxObject){
  if (ajaxObject.readyState == 4) {
     //do something with the response
  }
 }

 status is another property to consider - it indicates the status of sending request like 404 - not found, 200 = success, 304 = not modified
 The prev function  

 function takeAction(ajaxObject){
  if (ajaxObject.readyState == 4) {
     if (ajaxObject.status == 200 || ajaxObject.status == 304){ //response was sent succesfully 
          //do something with the response
     }
  }
 }

responseText is the response from the server
  function takeAction(ajaxObject){
  if (ajaxObject.readyState == 4) {
     if (ajaxObject.status == 200 || ajaxObject.status == 304){ //response was sent succesfully 
          //do something with the response
          alert(ajaxObject.responseText);
     }
  }
 }

 responseXML can be used when the response was sent as xml and the response header is "text/xml"
 All together
  function getAjaxObject(){
    var ajaxObject = false;
    if (window.XMLHttpRequest){
         ajaxObject = new XMLHttpRequest();
    }else if (window.ActiveXObject) {
      try{
        ajaxObject = new ActiveXObject("Msxml2.XMLHTTP");
      }catch(e){
         try{
          ajaxObject = new ActiveXObject("Microsoft.XMLHTTP");
         }catch(e){
           ajaxObject = false;
         }

      }
    }
    return ajaxObject; 
  }

  function entryPoint(){
    var ajaxObject = getAjaxObject();
     if (ajaxObject ){
    ajaxObject.onreadystatechange = function(){
      takeAction(ajaxObject); 
    };
    ajaxObject.open("POST","file.jsp", true);
    ajaxObject.setRequestHeader("Content-type", "application/x-www-form-urlencoded");
    ajaxObject.send("id=500&name=keith&age=18");
 }
 }
 function takeAction(ajaxObject){
  if (ajaxObject.readyState == 4) {
     if (ajaxObject.status == 200 || ajaxObject.status == 304){ //response was sent succesfully 
          //do something with the response
          alert(ajaxObject.responseText);
          var testDiv = document.getElementById("test");
          testDiv.innerText = ajaxObject.responseText; 
     }
  }
 }

 Processing Response Data
 The usual practice: response data can be in one of three formats: XML, JSON, HTML. And may be plain text.
 XML is the most common. example receive: var data = ajaxObject.responseXML; Here we can use the DOM functions to parse the XML data
 Example:
var data = ajaxObject.responseXML;
data.getElementsByTagName("name")
data.getElementsByTagName("name")[0]
data.getElementsByTagName("name")[0].firstChild
data.getElementsByTagName("name")[0].firstChild.nodeValue
Similarly, you can use other DOM functions

 To change the contents of the web-page dynamically, you can use the DOM methods like -- create, set, innerText, innerHtml (use carefully) methods. Check the JavaScript DOM article [846] in this web-site. adding and removing childs/elements may be required in some situations - DOM also supports that
 You can also send data as JSON from the server side like: JSON format: 


{"person":{
     "name":"Keith Tang",
     "school":"uofm"
  }
}
 Receiving and extracting information from JSON: [content type will be text]
 var data = eval('('+ ajaxObject.responseText +')');
 var name = data.person.name;
 var school = data.person.school; 
 
 Response data as HTML 
 The response can come as HTML. This may be useful, if only one area of the web-page is affected and we want to put the HTML response in that area. Otherwise it may not be great. Also, we need to use innerHTML method that was introduced by IE and later adopted by others. Still, it's not a standard (W3C)
 Example: The content type of response data should be text/html
       if (ajaxObject.status == 200 || ajaxObject.status == 304){ //response was sent succesfully 
          //do something with the response
          alert(ajaxObject.responseText);
          var testDiv = document.getElementById("test");
          testDiv.innerHTML = ajaxObject.responseText; 
     }





Firebird as an Alternative to Oracle/MS SQL Server/Interbase/Access


Note:



Firebird can be a very good alternatives to Oracle/MSSql Server/Interbase. First of all, it is free. It can be good enough for upto medium level of enterprises. Supported database size is more than 11 terabytes. For a single table 20GB. It also implements ACID properties well enough. Implements two phase commit and in record level locking and hence can provide more concurrency and connection.

It also implements MGA to provide recovery that also Oracle/MSSQL server imitated from interbase/firebird.

A well designed database and a well designed network using Firebird will be strong enough to support a mid - size company. Also, if the database is designed well and used the clean normalization, and used clean indexing, the query will be faster enough.

Linux platform is more suitable than windows platform for Firebird.

In 32 bit environment, Firebird server version support 2 GB of ram and hence around 450 concurrent connection. This is due to memory addressing in 32 environment, required cache size and for similar reasons.

In Linux 64 bit versions Firebird can provide better service and more concurrent connections. Firebird is not stable and reliable enough to be used with windows platform in 64 bit environment. Though, Firebird project, hopes to work on this.

Firebird, has a dedicated community to support the product. They provide supports through a discussion forum. (May be .. with some other ways). Firebird team also hopes to continue the project to fullfill future demand.

Being opensource project the database system seems will be strong enough and well designed and well featured to meet customer demand.

For details please check:


A detail discussion can be found here.
http://www.ibphoenix.com/main.nfs?a=ibphoenix&page=ibp_enterprise_firebird


Note:
Firebird can be a good option for a Midsize company in Bangladesh


Features of Firebird


What is firebird:

The software has two main components: the database server, which lives on the same host machine as the databases, and the 

application interface, commonly referred to as �the client library�. The client runs in the client pc or in the middleware 

for accessing through internet browsers.

The server's executable is less than 1.5 Mb and a full server installation, including all tools and documentation, takes 

up less than 10 Mb. 


Versions:

1.5 most stable and tested

firebird 2: Mid of year  2006

Vulcan: A parallel project used by SAS to move many of its business applications from Oracle to Firebird. 
Purpose:  redesigning the threading architecture of the database engine


Is Firebird �Enterprise Capable�?
stability, scalability, availability, capacity, interoperability and autonomy.

Stability


Stable enough, supports strongly ACID properties

Scalable??

Good enough but not extremely scalable

Firebird's upscaling is merely a question of adapting the environment. The same engine comfortably handles anything from 

being embedded in a stand-alone client application, through to a classical two-tier client/server LAN of around 750 

potential users, to incorporation in a multi-tier solution for thousands of potential clients. Database growth is 

effectively limited only by the disk storage available and can be split across multiple hard disks.

Through smart replication and good connection management in the access layers, the workload of a busy system can be 

distributed across multiple servers. For example, a well-resourced central server can handle the interactive demands of 

LAN, intranet or extranet (or all together) while a replicated server takes care of long-running jobs that need to isolate 

a snapshot of data for lengthy periods.

Availability

Among its users, Firebird has a reputation for being bomb-proof.


It uses optimistic locking at record level, drastically reducing the wait-time overheads in comparison to others where 

read-write transactions lock entire sets, even tables, pre-emptively. No tuning is ever required to facilitate handling 

varying workloads through the day or week. A database does not have to be shut down for backups. It can be replicated or 

shadowed for almost instantaneous cutover in the event of disk failure. It is robust and recovers immediately from power 

failure, without loss of database integrity.


Supports online backup.

Firebird is a popular choice for enterprises needing continuity of service around the clock. Command-line tools are 

distributed with the software for all administrative activities, allowing regular housekeeping to be automated as 

scheduled or on-demand jobs. A Services API is also available to wrap admin tasks into a program or service application.



Firebird Databases as the Back-end to Enterprise Software Systems 



Who Uses Firebird?
Because Firebird is free, there are no licences to count, no beans to count. It is known, from reputable enterprise surveys, that Firebird is chugging away on hundreds of thousands of production sites around the world. The following is a selection of companies and organisations that are publicly known to be using Firebird:

Broadview Software Ltd, Toronto, Canada, vendor of information and control systems and online services for broadcasters worldwide

Morfik P/L, Hobart, Tas., developers and vendors of WebOS development suite for construction and maintenance of interactive websites, stores web objects in a Firebird meta-layer (system database) as well as Firebird user data.

Communicare Systems Pty Ltd, Perth, WA, vendor of patient management and medical records software for hospitals, clinics, medical practices and mobile health units across Australia.

�The Examiner� newspaper, Launceston, Tas., high availability(24/7) business, information, production and news systems.

U.S. Navy, broad range of management and logistical systems

Frontrange Solutions USA Inc., Colorado Springs, U.S.A, as the back-end of the highly scalable, award-winning integrated CRM, service management and business systems �Goldmine� software suite.

British Rail, U.K., timetabling, bookings, accounting and information systems for national railway passenger network. 

Deutsche Presse-Agentur GmbH, HQ in Hamburg, Germany, largest press agency in Germany, provides a worldwide service to newspapers, magazines, TV and radio news networks.

KIMData, Munich, Germany, business intelligence systems and data warehousing for German hospitals.


Comparison: FireBird, MySQL, PostGreSQL


PosTGRESQL Provides better query responsetime than firebird and MySql. Firebird stands somewhere in the middle. A 

little longer response time than PostGreSql.


http://benchw.sourceforge.net/benchw_results_open3.html


Several PostGreSQL versions are compared at:


http://benchw.sourceforge.net/benchw_results_postgres_history.html

Several MySQL versions are compared at:


http://benchw.sourceforge.net/benchw_results_mysql_indexes.html

A good comparison among these databases will be found at:

http://www.geocities.com/mailsoftware42/db/



Mentionable comments

PostGreSQL Supports 400+GB DB.
One source: As for each connection it forks new thread, it is bit slower than MySql: Another source: postgresql is faster 

than mysql. Seems the truth is: for single connection postgresql can be faster but for multiple connections mysql is 

faster. just an information, not sure yet.

New PostGre Features
http://www.postgresql.org/docs/whatsnew

Some mentionable comments: Supports SMP and almost linearly improves performance witth multiprocessor system.

Supports roles, in/out parameters/two phase commit/table partitioning shared row locking(firebird record level 

locking), 64 bit shared memory hence supports two terabytes of ram


PostGreSQL capability

4.4) What is the maximum size for a row, a table, and a database?
These are the limits:


Maximum size for a database? unlimited (32 TB databases exist) 

Maximum size for a table? 32 TB 

Maximum size for a row? 400 GB 

Maximum size for a field? 1 GB 

Maximum number of rows in a table? unlimited 

Maximum number of columns in a table? 250-1600 depending on column types 

Maximum number of indexes on a table? unlimited 


One limitation is that indexes can not be created on columns longer than about 2,000 characters. Fortunately, such indexes 

are rarely needed. Uniqueness is best guaranteed by a function index of an MD5 hash of the long column, and full text 

indexing allows for searching of words within the column.


Source:

http://www.postgresql.org/docs/faqs.FAQ.html



4.20) What replication solutions are available? 
Though "replication" is a single term, there are several technologies for doing replication, with advantages and 

disadvantages for each.


Master/slave replication allows a single master to receive read/write queries, while slaves can only accept read/SELECT 

queries. The most popular freely available master-slave PostgreSQL replication solution is Slony-I.


Multi-master replication allows read/write queries to be sent to multiple replicated computers. This capability also has a 

severe impact on performance due to the need to synchronize changes between servers. PGCluster is the most popular such 

solution freely available for PostgreSQL.


There are also commercial and hardware-based replication solutions available supporting a variety of replication 

models.



Important Notes
Server Configuration 
A number of postgresql.conf settings affect performance. For more details, see Administration Guide/Server Run-time 

Environment/Run-time Configuration for a full listing, and for commentary see 

http://www.varlena.com/varlena/GeneralBits/Tidbits/annotated_conf_e.html and 

http://www.varlena.com/varlena/GeneralBits/Tidbits/perf.html. 



Hardware Selection 

The effect of hardware on performance is detailed in http://www.powerpostgresql.com/PerfList/ and 

http://momjian.us/main/writings/pgsql/hw_performance/index.html. 




Wikipedia link for postgressql-http://en.wikipedia.org/wiki/PostgreSQL

EnterpriseDB kind of commercial but cheap based on postgressql 



PostGreSQL Limitations and solutions


http://searchopensource.techtarget.com/originalContent/0,289142,sid39_gci1172668,00.html

PostGreSQL Windows Installer
http://pgfoundry.org/projects/pginstaller/


Important Links for Mysql, PostGreSQL, Firebird, EnterpriseDB, Ingres


Firebird and postgresql:
http://www.linuxjournal.com/node/7010 


Important comment: easy to migrate from oracle to firebird than to postgre or mysql. From interbase to firebird will be better as they are similar.



http://forums.devshed.com/firebird-sql-development-61/mysql--vs--firebird-sql-62269.html : Firebird is far better choice than mysql


As for Performance, MySQL will outperform Firebird on almost all tests on local machine......


On a Network Server a properly designed Firebird Server will outperform MySQL on any Test and the network-Traffic generated by Mysql will be many times higher than Firebird

So you decide the one you need according to your needs .....



This link also compares fb with potgre and favors fb as the author's background is borland

Why Postgress is  better than firebird

Firebird is not as good as PostgresQL (Score:0) 
By Anonymous Reader on 2004.12.03 2:21 (#102703) 
And here is why:

1. Firebird has no temp table support.
2. Firebird uses several SQL modes i.e DSQL which only works client side and PSQL which only works in procs. All sql works in Postgres functions.
Try creating a table or a user in a Firebird proc...ooops can't be done.
3. Firebird databases grow out of control and have to be backed up restored on a regular basis.
4. Firebird has a concept of a OAT (oldest active transaction counter) if this counter gets stuck all transactions get held up and your DB size goes through the roof and performance goes to the basement.
5. Firebird has virtually no built in functions and flakey UDFs must be used. Postgres on the other hand has every function you can think of.
6. Postgres has many rich procedural languages including perl,TCL,Java and C# in the works.

I could go on.... Version 8 of Postgres which will be released soon adds point in time recovery, Try except error handling in functions, table spaces and more.

I converted all my apps from Firebird 1.5 to Postgresql 7.4 and I would never use Firebird again on Unix or Windows 


Why PostGress better than FireBird: This comparison may not be accurate though.


Postgres Vs Interbase/Firebird (Score:0) 
By Anonymous Reader on 2004.12.03 18:23 (#102740) 
http://www.vitavoom.com/postgresql.html

Firebird has not true text type you must use the clumsy blobs and weird blob subtypes.

Postgres is much closer for enterprise use than Firebird.

almost all of this applies to Firebird as well as interbase.

PostgreSQL vs Interbase
PostgreSQL...

        * ... has no "dialects" or other weird features.
        * ... has no "backdoors" which can compromise your whole company's security and business (check here and here).
        * ... supports unlimited row sizes, unlimited datasebase sizes, tables up to 16TB (!!), unlimited number of rows, unlimited indexes for table and 1Gb per field.
        * ... has a boolean field.
        * ... can cancel a query asynchronously (Interbase 6.5 - the commercial version - seems to support it now).
        * ... has a flexible (not fixed) types system, and supports more types then Interbase. You can always add your own types at your wish, or change existent types behavior. PostgreSQL even has geometrical and IPv4 types support (!!).
        * ... supports inheritance.
        * .. supports flexible full text indexing through OpenFTS.
        * ... has a much more sofisticated locking mechanism (MVCC).
        * ... has arbitrary precision numeric fileds (numeric type).
        * ... is resistant to crashes and power failures (by using it's logging system, MVCC and chepoint)). Although it is technically possible that a database gets corrupt, we at Vita voom never saw it (except for corrupt media storage of course).
        * ... supports functions (whose can be used as stored procedures). These functions current can be written on SQL, pl/PgSQL (a language similar to Oracle's pl/SQL), TCL, Perl, and Python, C, C++ (or other compiled languages) but it's not limited to them.
        * ... can have functions to define default values for columns (providing ultimate default value flexibility).
        * ... supports much more arrays types then Interbase, they are more flexible and can support much more elements.
        * ... supports rules.
        * ... supports "fetch" SQL command to get only a limited number of rows at a time, making queries more responsive and resource economic.
        * ... has regular expressions support (for searches and operations).
        * ... has a 'EXPLAIN' command which will show will how it will perform a query, so that you optimize it.
        * ... has statistics about database usage which can be used to optimize queries and indices.
        * ... has sequences.
        * ... has more built-in functions then Interbase (or any other open source RDBMS).
        * ... supports indexes on functions.
        * ... has broader subselects support then Interbase.
        * ... has a more flexible BLOB fields support.
        * ... can limit the number of rows retrieved at at time (with the 'LIMIT' keyword).
        * ... is more standards-compliant then Interbase.
        * ... allo 


Speed: Firebird vs. PostGreSql


Please read.
According to this article postgresql faster than firebird. But I also got information/tests where firebird is faster than postgresql.

http://archives.postgresql.org/pgsql-advocacy/2003-06/msg00280.php

However,  Speed may not be the only factor to select a database product. We can improve raw speed in many alternate ways, hardware solutions, ram, faster storage, faster CPU. To compare speed issue, efficiency issue, we need to take a look how the query optimizations are implemented in databases. How, the joins, inner joins, outer joins are implemented. How multiple joins are implemented. Also, indexing is a factor that also affects performance issue. We can try creating same database and using a queries that are simple to complex and run on both databases and see, how well they perform.

Postgresql   supports SMP (multiple processor system) and provides better efficiency in multiprocessor systems. Firebird, is not still matured in SMP environment.

 Firebird supports 32 bit environment, still not stable/reliable enough for 64 bit env. It supports max ram of 2 gb and hence 150 -  450 concurrent users. Postgresql supports 2 TB of ram in a single server. For both of them, we can implement multiple servers with master/slave relation for better performances. 

Tools to create ER diagrams from a database dynamically



Microsoft Visio, and dbVisualizer provide features to create ER diagrams from existing database tables.

Why needed?
ER diagram is very useful to understand the total
database structure that helps a new programmer to work on the existing databases more efficiently.

Visio:
While creating Database diagrams, a menu item named database is displayed. Reverse Engineering option under Database menu helps to create ER diagram from 

existing database tables. Before that, target database drivers for visio need to be installed. If the database is in db2/mysql/postgresql, then  

db2/mysql/postgresql drivers for visio should be installed. From Database/options/drivers, the driver needs to be configured. Afterwards, Reverse Engineering 

option may be used to create the ER diagram. There is no suitable driver for postgresql databses for Visio. ODBC drivers may be used for the purpose (the ER 

diagram may not be accurate from ODBC driver for postgresql). 

dbVisualizer:
In dbVisualizer, when the TABLEs group/option is selected in the left pane in the right/middle pane there will be a references option. When the references 

tab is selected, an ER diagram is displayed using all tables. The ER diagram can be displayed as Hierarchical, circular, orthogonal, or organic. There are 

options for the purpose.

When a single table name is selected, the table and the associated tables are displyed in an ER diagram.

In the rightest column, selected tables option allows to create ER diagrams only for the selected tables. When 'selected tables' is clicked a list is 

displayed in a dialogbox. Tables can be selected from this list (use control key). Build graph  option creates and displays the ER diagram.



Normalization (1NF to 5th NF)


Please check this link.

http://www.keithjbrown.co.uk/vworks/mysql/mysql_p7.php

DBMS System Online Course


Please check the resources at:

http://www.cs.sfu.ca/CC/354/zaiane/material/notes/contents.html



Just like an undergraduate course in Database Management Systems. Along with other topic, ER-Diagram and representation of ER-Diagrams into tables are provided. Some of the complex forms of ER diagrams are discussed.


Practical Database Design Resources



http://www.dbpd.com/vault/9804date.htm
http://cs.senecac.on.ca/~dbs201/pages/Normalization_Practice.htm
http://cisnet.baruch.cuny.edu/holowczak/classes/3400/norm_ex.html
http://thecommunityengine.com/bit320/syllabus/
http://www.ibm.com/developerworks/web/library/wa-dbdsgn2.html
http://www.phpbuilder.com/columns/barry20000731.php3
http://www.devx.com/ibm/Article/20859
http://www-128.ibm.com/developerworks/web/library/wa-dbdsgn1.html
http://www.devx.com/ibm/Article/20702



Normalization in Relational DBMS Systems



First Normal Form:


All table columns should have distinct meaning

In another word: All attributes of an entity/table must be unique

Solution: 

Grow the table row wise[in the direction of rows] not the column wise
Group the columns with same meaning into one
To handle multiple values for the same attribute of an entity create multiple rows [not multiple columns]

To keep track of paycheques, you may think the table should be as follows:

Name, provider company, date 1, pay cheque 1, date2 , pay cheque 2, date 3, paycheque 3

See date1, date2, and date 3 have the same meaning
Pay cheque 1, Pay cheque 2, and Pay cheque 3 have the same meaning
These are the repeating attributes

Solution:
create table with:

number name, company, date,   paycheque
100    1,    xyz,      12/13,  1000.00
100    1,    abc,      12/13,  1000.00
100    1,    xyz,      12/31,  1000.00

or 

create a child entity with Date and amount. And a master entity with number, Name and Company
Entity one: number, name, company
Entity two: number, date, amount


2nd Normal form:
----------------

Rule: 

All attributes can be identified from the primary key. Primary key is directly related to all other attributes.
All attributes are fully dependent on the primary key.

Line Item Table/Entity:
--------------------
number [line item] [pk]
order number[pk]
vendor name
vendor town
product code
product amount

Here, vendor name and vendor town may not be fully dependent on the whole primary key. They are dependent on the order number.
So we can decompose it into another table.

Order entity
Number [pk]
Vendor Name
Vendor Town

Lineitem entity

number [pk]
order_number [pk]
product code
product amount


3rd normal form
-----------------
Rule: Non key attributes are fully dependent on the primary key but not on any other key or attribute.
In Order entity table, vendor town is not fully dependent on number[pk], but it does depend on the vendor name. So we can decompose order entity table into two

Vendor Entity
Name [pk]
Town

Order Entity
Number
vendor-name









Boyce/Codd and Fourth Normal Form



Boyce/Codd Normal Form

----------------------

It is just an extension to the third normal form. Third normal form ensures that non key attributes does not depend on any non key attribute but fully depend on the key[primary] attributes.



Boyce codd normal form ensures that non key attributes are fully dependent on the total set of the primary key. Non-key attributes should not 
depend [only] on a subset of the key[primary] attributes.



Fourth Normal Form:

-------------------

It tries to decompose an entity/table into multiple entities/tables when there are multiple independent[not dependent on each other] multivalued attributes in an entity/table.



For example: Consider a table with emp_number, skill name, objective of the employee. Employees may have many skills and also many objectives. Hence, skill_name, and objective are multivalued and also they do not depend on each other. This table will cause many redundant data.Better is to use two tables like:



Emp_skill

Emp_num, Skill Name



Emp_objective

Emp_num, Objective





Logical Data Modeling: Logical Database Design Steps: RDBMS



Logical Data Modeling 

   

       Identify major entities
      
 Determine relationships between entities
      
 Determine primary and alternate keys
      
 Determine foreign keys
      
 Determine key business rules
      
 Add remaining attributes
      
 Validate user views through normalization
      
 Determine domains
      
 Determine triggering operations
      
 Combine user views
      
 Integrate with existing data models
      
 Analyze for stability and growth    
   

Translate Logical Model into the Real Database System

    Identify tables
   
 Identify columns
   
 Adapt data structure to product environment
   
 Design for business rules about entities
   
 Design for business rules about relationships
   
 Design for additional business rules about 
        attributes 
   
 Tune for scan efficiency
   
 Define clustering sequences
   
 Define hash keys
   
 Add indexes
   
 Add duplicate data
   
 Redefine columns
   
 Redefine tables


Design for Special Design Challenges

   Provide for access through views
  
 Establish security
  
 Cope with very large databases
  
 Access and accommodate change
  
 Anticipate relational technology evolution

Reference: C. C. Fleming and B. V. Halle




PHP Security: Coding that Maintains Security


Php Security

PHP can be included as a module to the web-server, or executed as a separate executable binary. In either case, it can access files, execute commands, open network connections in the server. Further, PHP can be used to write scripts with all the power of the shell users. Hence, anything running on that server may face security problems. Though, careful coding will reduce the risks to a great extent[php.net].


Common security risks in PHP[Abdul Basit, php.net]

Most common are :


1-Invalidated Input Errors
2-Access Control Flaws
3-Session ID Protection
4-Cross Site Scripting (XSS) Attacks
5-SQL Injection Vulnerabilities
6-Error Reporting
7-Data Handling Errors
8-PHP configuration settings



PHP Security when installed as a CGI Binary[php.net]

 Do not place any interpreters into the cgi-bin directory
 Even If PHP is installed as a standalone binary (and in cgi-bin directory), PHP can prevent attacks that may arise from such setting.
Accessing system files: http://my.host/cgi-bin/php?/etc/passwd -- using such URLs can be risky, the part after ? may be treated as command line arguments to the interpreter, and hence, in some cases pose risks

Accessing any web document on server: 

http://my.host/cgi-bin/php/secret/doc.html -- this way can also be risky 


PHP compile time options such as --enable-force-cgi-redirect and runtime configuration directives doc_root and user_dir can be used to prevent such risks.


PHP and IBM DB2


IBM-DB2: Random stuffs.

This is a great book on IBM-DB2. If you are experienced with DBMS systems like SQL Server, Oracle, MySQL, the first thing you may want to look at the features that are supported by IBM-DB2. Then you can try to find out the differences among them. It really will make your learning much faster. Then just skim through page by page, when you are at the end of the book, you will find you are ok to work with IBM-DB2.
http://publib-b.boulder.ibm.com/Redbooks.nsf/RedbookAbstracts/sg244249.html

PHP has concepts like PDO and PDO_ODBC, and generic odbc features that will allow you to connect to and work with DB-2 databases. Generic odbc is the general/procedural way to connect to. PDO and PDO_ODBC are object oriented ways. PDO works with native IBM drivers. PDO_ODBC uses odbc connections to the DB2. For PHP you need to install drivers to support DB2. I worked with PDO_ODBC to connect to DB-2 databases in IBM iSeries servers. You need to install odbc db2 drivers for iseries servers. Then in /etc/odbcinst.ini file you need to mention driver specifications and in /etc/odbc.ini, you need to mention the odbc dsn name, database name, and some other parameters to connect to the database. Though, you may also supply some parameters in the PDO_ODBC connect method.

For details on PHP and DB2, please check:

http://www.redbooks.ibm.com/redbooks/pdfs/sg247218.pdf




A Sample PHP Class



A sample PHP class is provided below. How the class is used? 



When the submit button from the interface (web-page) will be clicked the code in the form-action web-page will call the the create method (static) to create a Ticket data/row in the database table Ticket. The method call will look like Ticket::create(array with field=>value pair, as formed with form submitted data) and you will get an Ticket object created with the inserted row/data.



To update a Ticket, you can create the Ticket object (constructor will do it for you) as you will know the Ticket id at this time. Then use the appropriate set method to update the value in the database. 



To search call the static search method with a list/array of field=>value pair. 



$dbh (read-only) and $dbhWrite(read-write) are global variables that represent connections to the database.
 



//represents a customer submitted Ticket
class Ticket
{
	public $parentTicket;
	private $dbh_;

	//member variables, named after the column names of the databse table - Ticket
	private $id_;
	private $type;
	private $subject_;
	private $timestampCreated_;
	private $timestampUpdated_;
	private $status_;
	private $parentTicketId_;
	private $categoryId_;
	private $categoryName_;
	private $internalNotifylist_;
	private $externalNotifyList_;
	private $customerId_;
	private $customerName_;
	private $creatorId_;
	private $creatorName_;
	private $ownerId_;
	private $assignedTo_;

	//constructor, creates a Ticket object with the table row with id = $id
	public function  __construct($id)
	{
		global $dbh;
		$this->dbh_ = $dbh;
		$this->refreshValues($id);
	}


	public function refreshValues($id)
	{

		$query="Select Ticket.*, TicketCategory.name
  from Ticket left join TicketCategory on Ticket.categoryId 
= TicketCategory.id
				where Ticket.id=$id";

		if ($result=$this->dbh_->query($query))
			if($result->num_rows==1)
			{


				$row=$result->fetch_object();

				$this->id_ = $id;
				$this->type_=$row->type;
				$this->subject_ = $row->subject;
				$this->timestampCreated_ = $row->timestampCreated;
				$this->timestampUpdated_ = $row->timestampUpdated;
				$this->status_ = $row->status;
				$this->parentTicketId_ = $row->parentTicketId;

				if($this->parentTicketId_>0)
					$this->parentTicket=$row->parentTicketId; //new Ticket($this->parentTicketId_);
				else $this->parentTicketId=0;

				$this->categoryId_ = $row->categoryId;
				$this->categoryName_ = $row->name;
				$this->internalNotifyList_ = $row->internalNotifyList;
				$this->externalNotifyList_ =$row->externalNotifyList;
				$this->customerId_ = $row->customerId;
				$this->creatorId_ = $row->creatorId;
				$this->ownerId_ =$row->ownerId;
				$this->assignedTo_ =$row->assignedTo;

				return true;
			}
			else
				return false;
	}

	//methods to retrieve/set data/member variables

	//retrieve id
	public function getId()
	{
		if($this->id_>0) return $this->id_;
		else return false;
	}
	//set id
	public function setId($id)
	{
		if (is_numeric($id))
		{
			if ($this->setField('id',$id)) return true;
			else return false;
		}
		else return false;
	}

	public function getCustomerId()
	{
		if($this->id_>0) return $this->customerId_;
		else return false;
	}
	public function setCustomerId($customerId)
	{
		if (is_numeric($customerId))
		{
			if ($this->setField('customerId',$customerId))
				return true;
			else return false;
		}
		else return false;
	}

    //used by methods to set member variables
	private function setField($field, $value)
	{
		$dbhWrite=getDbhWrite();
		$query="update Ticket set 
$field='".$dbhWrite->escape_string($value)."' where 
id=$this->id_";

		$result = $dbhWrite->query($query);
		if ($result==true)
		{
			if($dbhWrite->affected_rows==1)
			{
				$this->setTimestampUpdated();
				$this->refreshValues($this->id_);
				return true;
			}
			else return false;
		}
		else return false;
	}

    //used to create an entry into the Ticket table (database).
    //After insertion this row is used to form a Table object and returned to the caller
	static public function create($fields)
	{
		$dbhWrite=getDbhWrite();
		$timestamp = time();
		$parentTicketId='null';
		$customerId='null';
		$ownerId='null';
		$assignedTo='null';
		$categoryId='null';
		$type='null';

		foreach($fields as $field => $value)
		{
			switch($field)
			{
				case "type":
					if(self::isPermittedType($value)) $type=$value;
					else return false;
					break;
				case "status":
					if(self::isPermittedStatus($value)) $status=$value;
					else return false;
					break;
				case "subject":
					if (is_string($value))
						$subject=$dbhWrite->escape_string($value);
					else
						return false;
					break;
				case "parentTicketId":
					if(is_numeric($value))
						$parentTicketId=$value;
					break;
				case "categoryId":
					if(is_numeric($value))
						$categoryId=$value;
					break;
				case "customerId":
					if(is_numeric($value)) $customerId=$value;
					else return false;
					break;
				case "creatorId":
					if(is_numeric($value))
						$creatorId=$value;
					else return false;
					break;
				case "ownerId":
					if(is_numeric($value))
						$ownerId=$value;
					break;
				case "assignedTo":
					if(is_numeric($value))
						$assignedTo=$value;
					break;
			}
		}


		$insertStr = "insert into Ticket 
(type,subject, timestampCreated, timestampUpdated, status, 
parentTicketId, categoryId, customerId, creatorId, ownerId, 
assignedTo) values ($type, '$subject', $timestamp, 
$timestamp, $status, $parentTicketId, $categoryId, 
$customerId, $creatorId,$ownerId,$assignedTo)";

		$result = $dbhWrite->query($insertStr);

		if ($result == true)
		{
			if ($dbhWrite->affected_rows==1)
			{
				$ticket=new Ticket($dbhWrite->insert_id);
				return $ticket;
			}
			else return false;
		}
		else return false;

	}



	//searches the entire ticket table based on supplied field=>value pairs
	static public function searchFields($fields,$orderBy='id')
	{
		global $dbh;

		$query="select * from Ticket where ";
		foreach($fields as $field => $value)
		{
			if($value[0]=="!") //checking for not equal condition
			{
				$value=substr($value,1);
				$query.="`".$dbh->escape_string($field)."`!='".$dbh->escape_string($value)."' and ";
			}
			else
				$query.="`".$dbh->escape_string($field)."`='".$dbh->escape_string($value)."' and ";
		}
		$query=substr($query,0,-5);
		$query.=" order by ".$dbh->escape_string($orderBy);
		$result = $dbh->query($query);

		if ($result)
		{

			if ($dbh->affected_rows>0)
			{
				$tickets = array();
				$tickets = Ticket::processResult($result);
				return $tickets;
			}
			else return false;
		}
		else return false;
	}


    //used by searchFields method. Converts a set of retrieved data rows into array of objects.
	static private function processResult($result)
	{
		if($result->num_rows >= 1)
		{

			$tickets=array();
			while($row=$result->fetch_object())
			{
				$tickets[] = new Ticket($row->id);
			}

			return $tickets;
		}
		else return false;
	}





}




MVC for PHP



 

    http://www.phpmvc.net/
 


PHP Content Management Systems



  

       What is a Content Management System (CMS)? I think, I can consider the skeleton/framework that I am using for this web-site is a simple CMS. I developed the framework completely on my own from the scratch. Many times, I thought based on the code, I should release a open source CMS system for further development or create a CMS system for web-publishers and sale it. Though never happened, still it runs on my head sometimes, may be one day. This web-site includes CMS like features such as:
     
          I have an administration area from where I can administer the articles and video trainings/tutorials
         
 I have a user registration and permission set-up area where I can create new users and assign permissions. Also users can register.
        
 I have a user subscription and emailing (news letter) system
        
 I can create new categories and sub-categories both for articles and training videos under my administration area
        
 The left menu is dynamically generated from the database, I can change the display order of the items.
        
 At this moment, the web-pages are divided into separate sections such as, left, right, top, bottom, and body. Each one uses a separate file (is included in the main file). The article is taken from the database (though file based system may be search engine friendly, will go that route soon). I could create a section in the administration area to upload banner and content for the top section. I could create a section to provide contents for the left/right menu. Also, could provide options to insert user login, survey, quiz, live chat and related components to be inserted in the right or left menu.
      
 From the administration window, I can create books based on the articles. There are options to create multiple chapters and select articles for each chapter. I can create both HTML and PDF books.
     
 Administration window also allows traversing through the articles and editing them
     
 You can also include video contents
      
 More that I could do, I could control the subscription fee from the administration window, control whether the search engine will be there or not, where the search engine will be placed, provide different layout options, different themes, or select background from a collection of images or colors, change the font color and size 
    
 Could provide features to enable/disable user submitted articles, enable/disable/remove user comments
    
 I have many other plans with this web-site and will add many other features that will be controlled under the 
administration window
     
   
 Popular PHP CMSs/Frameworks:
         
              CMS Made Simple
            
  Drupal
            
  e107
            
  Joomla
            
  PHP Fusion
         
   
 How to start with Drupal
  


Comparison among some popular PHP CMSs



  

      Drupal/Joomla: Comparison Chart
     
 Comparing Open Source CMSes: Joomla, Drupal and Plone

 Drupal and Joomla comparison

 A Java-based CMS


  


MySql Administration SQL Commands


Using MySQL, Administration
Workshop Requirements
You should have access to the MySQL command line client software.

Various different PRIVILEGES on the MySQL Server

Introduction
In the other MySQL Virtual Workshops we have used commands that are pretty much applicable to anyone. This part of the MySQL series is aimed at giving a rudimentary understanding of managing a MySQL database server. As such the task covered here are not really about manipulating data or database structures, but the actual databases themselves.

Creating a Database
In order to create a database you need to have the PRIVILEGES- this may be because you are the root user or you (or you systems administrator) has created an admin user that has ALL PRIVILEGES over all databases. In these examples a user called 'admin' has been created precisely for this purpose. Creating a database is fairly straightforward.

Logging In
A reminder of how to start the MySQL Client Software, and as we are not concerned with manipulating just one database we don't have to specify a database as part of our startup command.

$ mysql -u  -p
Enter password:Create database command
Next we are ready to enter the very simple command to create a database which is:

mysql> CREATE DATABASE ; Let's imagine that we are going to create a 'vworks' database (those wishing to create a database for use with the VWs should use this). We would enter the command:

mysql> CREATE DATABASE vworks; We can now check for the presence of this database by typing:

mysql> SHOW DATABASES;
+-----------+
| Database  |
+-----------+
| mysql     |
| vworks    |
+-----------+
2 rows in set (0.06 sec)The other database listed ('mysql') is the internal database which MySQL uses to manage users, permissions etc. 

NOTE: Deleting or DROPing a database is similar to the DROP TABLE command issued in Part 4. e.g.

DROP DATABASE Granting Privileges on the new database
Now that we have created a database, we need to decide who gets to use it. This is done by granting permissions for a user to use the database. This has a simplified syntax of:

GRANT  
ON  
TO  
[IDENTIFIED BY ] 
[WITH GRANT OPTION]Where the items in square brackets are optional. The most common use is to give ALL PRIVILEGES on a database to a local user who has to use a password to access the database (in this case vworks).

mysql> GRANT ALL PRIVILEGES 
    -> ON vworks.* 
    -> TO newuser@localhost 
    -> IDENTIFIED BY 'newpassword';  If you are creating a database for use with the rest of the Virtual Workshops you should use this statement, substituting your username and password of choice. There are some other options we will look at. To restrict the user to manipulating data (rather than table or database structures) the statement would be altered to:

mysql> GRANT SELECT,INSERT,UPDATE,DELETE 
    -> ON vworks.* 
    -> TO newuser@localhost 
    -> IDENTIFIED BY 'newpassword';  So that the user can only change the data using SELECT,INSERT,UPDATE or DELETE statements. If you wished to give a non-local user permissions on the database (for use with remote clients) then you could designate an IP or host address from which the user can connect:

mysql> GRANT ALL PRIVILEGES 
    -> ON vworks.* 
    -> TO newuser@192.168.0.2 
    -> IDENTIFIED BY 'newpassword';  Now a user on the machine '192.168.0.2' can connect to the database. To allow a user to connect from anywhere you would use a wildcard '%'

mysql> GRANT ALL PRIVILEGES 
    -> ON vworks.* 
    -> TO newuser@'%' 
    -> IDENTIFIED BY 'newpassword';You could even decide that a user doesn't need a password if connecting from a certain machine. 

mysql> GRANT ALL PRIVILEGES 
    -> ON vworks.* 
    -> TO newuser@192.168.0.2But I think it is sometimes good to provide a password anyway. Finally we'll look at the WITH GRANT OPTION condition. This allows the user to give others privileges to that database:

mysql> GRANT ALL PRIVILEGES 
    -> ON vworks.* 
    -> TO newuser@localhost 
    -> IDENTIFIED BY 'newpassword' 
    -> WITH GRANT OPTION;  This would allow the user 'newuser' to log into the database and give their friend privileges to SELECT,INSERT,UPDATE or DELETE from the database.

mysql> GRANT SELECT,INSERT,UPDATE,DELETE 
    -> ON vworks.* 
    -> TO friend@localhost 
    -> IDENTIFIED BY 'friendpass';  The WITH GRANT OPTION usually signifies ownership although it is worth noting that no user can GRANT more privileges that they themselves possess.

Revoking privileges
Revoking privileges is almost identical to granting them as you simply substitute RE VOKE.... FROM for GRANT....TO and omit any passwords or other options.

For example to REVOKE the privileges assigned to a user called 'badvworks':

mysql> REVOKE ALL PRIVILEGES 
    -> ON vworks.* 
    -> FROM badvworks@localhost;  Or just to remove UPDATE, INSERT and DELETE privileges to that data cannot be changed.

mysql> REVOKE INSERT,UPDATE,DELETE 
    -> ON vworks.* 
    -> FROM badvworks@localhost;  Backing Up Data
There are several methods we can use to backup data. We are going to look at a couple of utilities that come with MySQL: mysqlhotcopy and mysqldump. 

mysqlhotcopy
mysqlhotcopy is a command line utility written in Perl that backs up (to a location you specify) the files which make up a database. You could do this manually, but mysqlhotcopy has the advantage of combining several different commands that lock the tables etc to prevent data corruption. The syntax (as ever) first.

$ mysqlhotcopy -u  -p  /backup/location/Which SHOULD copy all the tables (*.frm, *.MYI, *.MYD) into the new directory - the script does require the DBI perl module though. To restore these backup files simply copy them back into your MySQL data directory. 

mysqldump
This is my preferred method of backing up. This outputs the table structure and data in series of SQL commands stored in a text file. The simplified syntax is

$ mysqldump -u  -p  [] > file.sqlSo for example to back up a 'vworks' database which may have been created by completing the workshops:

$ mysqldump -u admin -p vworks > vworks.sql
After entering the password a 'vworks.sql' file should be created. When you look at this file you can actually see that the data and structures are stored as a series of SQL statements. e.g.:

-- MySQL dump 8.22
--
-- Host: localhost    Database: vworks
---------------------------------------------------------
-- Server version       3.23.52

--
-- Table structure for table 'artist'
--

CREATE TABLE artist (
  artistID int(3) NOT NULL auto _increment,
  name varchar(20) default NULL,
  PRIMARY KEY  (artistID)
) TYPE=MyISAM;

--
-- Dumping data for table 'artist'
--


INSERT INTO artist VALUES (1,'Jamiroquai');
INSERT INTO artist VALUES (2,'Various');
INSERT INTO artist VALUES (3,'westlife');
INSERT INTO artist VALUES (4,'Various');
INSERT INTO artist VALUES (5,'Abba');
And so on for the other tables. 

We could also have chosen to output just one table from the database, for example the artist table:

$ mysqldump -u admin -p vworks artist > artist.sqlWe could even dump all the databases out (providing we have the permissions).

$ mysqldump -u admin -p --all-databases > alldb.sqlRestoring a Dump
Restoring a dump depends on what you have actually dumped. For example to restore a database to a blank database (perhaps having transferred the sql file to another machine) it is fairly simple. 

$ mysql -u admin -p vworks < vworks.sql...or to add a non-existent table to a database...

$ mysql -u admin -p vworks < artist.sqlHowever, what happens if we want to restore data to an existing database (perhaps a nightly backup) ? Well we would have to add other options:

The equivalent of overwriting the existing tables would be telling the dump to automatically drop any tables that exist before restoring the stored tables. This is done with the ' --add-drop-table ' option added to our statement.

$ mysqldump -u admin -p --add-drop-table vworks > vworks.sqlThen restore like normal:

$ mysql -u admin -p vworks < vworks.sqlThe reverse might also be true. We may wish to create the database if it doesn't already exist. To do this we use the '--databases' option to specify the database we wish to back up (you can specify more than one).

$ mysqldump -u admin -p --databases vworks > vworksDB.sqlThis will create additional SQL statements at the start of each database that CREATEs the dumped database (checking first to see if it does indeed exist) then USEing that database to import the table data into.

-- Current Database: vworks
--

CREATE DATABASE /*!32312 IF NOT EXISTS*/ vworks;

USE vworks;
Again we can resort like normal, but of course this time we can omit the database name.

$ mysql -u admin -p < vworksDB.sqlOptimising a dump
There are a couple of options that are sometimes worth including when backing up and restoring large databases. 

The first option is '--opt', this is used override the mysql server's normal method of reading the whole result set into memory giving a faster dump. Example:

$ mysqldump -u admin -p --opt vworks > vworks.sqlThe second option is '-a' or '-all' (either will do). Which also optimises the dump by creating mysql specific CREATE statements that speeds up the restore:

$ mysqldump -u admin -p --all vworks > vworks.sqlUsing mysqldump to copy databases.
It is possible to combine a dump and a restore on one line by using a pipe '|' to pass the output of the dump directly to mysql basically bypassing the file. This may initially seem a bit redundant, but we can use this method to copy a database to another server or even create a duplicate copy.

For example to copy the 'vworks' database to a mysql server called 'remote.server.com':

$ mysqldump -u admin -p --databases vworks | \
> mysql -u backup -p MyPassword -h remote.server.com Note: the"\" at the end of the first line means you wish to contine the command on another line before executing it. 

You may, in certain circumstances, wish to make a copy of live data so that you can test new scripts and 'real world' data. To do this you would need to duplicate a local database. First create the duplicate database:

mysql> CREATE DATABASE vworks2; Then once appropriate privileges have been assigned we can copy the tables from the first table into the second.

$ mysqldump -u admin -p vworks | mysql -u backup -p MyPassword vworks2Notice in both these examples the second half of the line (after the pipe) passes the password as part of the connection statement. This is because asking for two separate passwords at the same time breaks most shells. That is why I have used a 'backup' user who can be granted permissions and have them revoked as necessary. 

Miscellaneous Leftovers
This final bit includes a few brief tricks that weren't really appropriate to include elsewhere, but are still worth noting.

Remote Client Connection
If you have set the privileges to allow remote connections to a database, you can connect from a remote command line client by using the -h flag:

$ mysql -u  -p -h For example to connect to a fictional vworks.keithjbrown.co.uk server:

$ mysql -u admin -p -h vworks.keithjbrown.co.ukNon-Interactive Commands
Sometimes you may wish to just do a quick look up on a table without the hassle of logging into the client, running the query then logging back out again. You can instead just type one line using the ' -e ' flag. For example:

$ mysql -u admin -p vworks -e 'SELECT cds.artist, cds.title FROM cds'

Enter password: 
+------------+------------------------------+
| artist     | title                        |
+------------+------------------------------+
| Jamiroquai | A Funk Odyssey               |
| Various    | Now 49                       |
| westlife   | westlife                     |
| Various    | Eurovision Song contest 2001 |
| Abba       | Abbas Greatest Hits          |
+------------+------------------------------+


Securing MySQL Database


After installing mysql, we will need to remove test database and associated users and their permissions. We will need to use mysql database to remove associated users and permission.







--
DROP DATABASE test; 




--
SELECT db.Host, db.Db, db.User, db.Select_priv 
    -> FROM db WHERE (db.DB = "vworksDB");




---
SELECT db.User, db.Host, db.Db 
    -> FROM db 
    -> WHERE (db.Db LIKE 'test%');




---
DELETE FROM db 


    -> WHERE (db.Db LIKE 'test%');


---


mysql> DELETE FROM db 


    -> WHERE (db.Host = "%");




mysql> DELETE FROM db 


    -> WHERE (db.User = "");


---
SELECT user.Host, user.User 


    -> FROM user 


    -> WHERE ((user.Host = "%") OR (user.User = ""));


---


DELETE FROM user 
    -> WHERE ((user.Host = "%") OR (user.User = ""));
---


FLUSH PRIVILEGES;
---


details: http://www.keithjbrown.co.uk/vworks/mysql/mysql_pA.php#secure

Joins in MySQL


Cross-Join: All row by all row, ex: SELECT  
FROM , 



The Equi-Join or Inner Join:
Syntax: 


SELECT  

FROM ,  

WHERE (Table1.column = Table2.column)





SELECT cds.artist, cds.title, genres.genre 

    -> FROM cds, genres 

    -> WHERE (cds.genreID = genres.genreID);





The Left Join:


Syntax:




SELECT  

FROM  

LEFT JOIN  

ON Table1.column = Table2.column



Without adding a WHERE clause the Left Join produces the same results as the equi-join example above.


mysql> SELECT cds.artist, cds.title, genres.genre 

    -> FROM cds 

    -> LEFT JOIN genres 

    -> ON cds.genreID = genres.genreID; 



The USING Clause: You can use this if the columns you are carrying out the join on have the same name. 


Syntax:



SELECT  

FROM  

LEFT JOIN  

USING ()





UPDATE JOIN:


mysql> UPDATE cds, artists 

    -> SET 

    -> cds.title = 'The Funkship Odyssey', 

    -> artists.Artist = 'George Clinton'

    -> WHERE (artists.artistID = cds.artistID) 

    -> AND (cds.cdID = '2');







UPDATE cds->LEFT JOIN artists 

    -> ON cds.artistID = artists.artistID

    -> SET 

    -> cds.title = 'A Funk Odyssey', 

    -> artists.name = 'Jamiroquai'

    -> WHERE (cds.cdID = '2');





DELETE Joins:


mysql> DELETE cds 

    -> FROM cds, artists 

    -> WHERE (cds.artistID = artists.artistID) 

    -> AND (cds.artistID = '3');







MySQL Resources


Mysql Resources:
First you need the latest/stable version of MySQL. Right now 6.0 is the latest version. Mysql has two different releases like:

community server[free] 

enterprise server[commercial]



Note: MAXDB is the current full package with many features that may not be fully tested. 



Download MySQL:
You can download MySQL from



http://dev.mysql.com/downloads/mysql/5.0.html 



Check the lower portion of the webpage.



Working with Mysql:
After installation you can interact with MySQL server through command line[Best to become guru]. But you may also want to use GUI IDE to interact with. GUI tools can be downloaded from:



http://dev.mysql.com/downloads/gui-tools/5.0.html 





GUI are of two types: to administer MySQL server. Used for backup, restore, security 



Development: For creating Database and interact with database using tables, Queries, Stored procedures, triggers






Application Development:

You can build appications that use MySQL databases at the backend. You can use languages like PHP, Perl, Java, .net to interact with MySQL databases. Usually, the package for these languages contain a driver to provide the functionalities. Otherwise, you can download drivers from:



http://dev.mysql.com/downloads/connector/ 



for many different programming languages like Java, PHP, Perl and similar.




MySQL Resources: MySQL Start


Mysql Resources:
First you need the latest/stable version of MySQL. Right now 6.0 is the latest version. Mysql has two different releases like:

community server[free] 

enterprise server[commercial]



Note: MAXDB is the current full package with many features that may not be fully tested. 



Download MySQL:
You can download MySQL from



http://dev.mysql.com/downloads/mysql/5.0.html 



Check the lower portion of the webpage.



Working with Mysql:
After installation you can interact with MySQL server through command line[Best to become guru]. But you may also want to use GUI IDE to interact with. GUI tools can be downloaded from:



http://dev.mysql.com/downloads/gui-tools/5.0.html 





GUI are of two types: to administer MySQL server. Used for backup, restore, security 



Development: For creating Database and interact with database using tables, Queries, Stored procedures, triggers






Application Development:

You can build appications that use MySQL databases at the backend. You can use languages like PHP, Perl, Java, .net to interact with MySQL databases. Usually, the package for these languages contain a driver to provide the functionalities. Otherwise, you can download drivers from:



http://dev.mysql.com/downloads/connector/ 



for many different programming languages like Java, PHP, Perl and similar.




Stored Procedure in MySql


Starting from MySQL 5, you get Stored Procedure in Mysql

What is a stored procedure: A stored procedure is simply a procedure that is stored on the database server like MySQL. In programming languages, you write procedures to execute a function/logic. You can write similar procedure in SQL and store it in the database. From the front end application you can just call the procedure to get the functionality. Usually, you send series of sqls to the databases to execute a logic. A stored procedure is better as it needs one single call. But not every logic can/should be implemented as stored procedures.

 Sample stored procedure

CREATE PROCEDURE sp_hello() 

SELECT 'Hello World';




 It just creates a procedure. To run the procedure, you have to type 


call sp_hello; 


You will see 'Hello World' as output.

Stored procedures can also take parameters and return values. Both needs to be mentioned as parameter. In the parameter list we can declare a variable as IN, OUT, or INOUT parameter. You can use SQLs[insert,select] inside procedure to perform database operations. Also, you can use to set/unset session variables.

Session variable example

SET @X=100;

CREATE PROCEDURE sp_in(p VARCHAR(10))

SET @x = P;


call sp_in(1000);
 You see 1000 in screen

A more practical stored procedure with multiple statements

mysql> DELIMITER |
mysql> CREATE PROCEDURE sp_declare (P INT)
    -> BEGIN
    ->  DECLARE x INT;
    ->  DECLARE y INT DEFAULT 10;
    ->  SET x = P*y;
    ->  INSERT INTO sp1(id,txt) VALUES(x,HEX('DEF'));
    -> END|

Query OK, 0 rows affected (0.00 sec)
 
mysql> DELIMITER ;
mysql> CALL sp_declare(4);

 please, note the use of | and DELIMETER. They provide support so that you can use ; in your procedures.

Some stored procedure related SQL commands
SHOW PROCEDURE STATUS
SHOW CREATE PROCEDURE Hello
SELECT * FROM INFORMATION_SCHEMA.ROUTINES [Ansi standard]

Thanks
Sayed

MySQL Reference Manual



    MySQL Reference Manual


MySQL: Special Interests



 

     Optimization
    
 MySQL Load Balancher
    
 MySQL Replication
    
 MySQL Cluster
    
 Stored Procedures and Functions
    
 MySQL High Availability and Scalability

 


Configuring IIS 6.0


Please check:



http://www.microsoft.com/technet/prodtechnol/WindowsServer2003/Library/IIS/0a199196-4ae9-41eb-b8c1-572251f9f550.mspx?mfr=true



It is a very good resource



Check the following link to know in 2003 server that runs IIS what services should be enabled/disabled



http://www.microsoft.com/technet/prodtechnol/WindowsServer2003/Library/IIS/eb255518-2cc7-4972-8dd9-40bbaa7ca331.mspx?mfr=true




Common Administrative Tasks:
http://www.microsoft.com/technet/prodtechnol/WindowsServer2003/Library/IIS/f504d2a6-be2a-49fa-b3e9-931ab1671bf1.mspx?mfr=true


WebLogic and WebSpheres



I was just checking about weblogic and websphere. Some resources that I went through:


   Compare Weblogic and Websphere
 Book: BEA Weblogic Server Bible
 Websphere Tutorial

Note: Sometimes knowing information like where to get the information is important especially when you know if you read, you will understand, and if you understand, you will be able to implement.


Installing Apache Tomcat 6.0: Windows



   Make sure you have installed J2SE 5 (both the jdk and the jre) or greater (for tomcat 6.0, j2se5 is required according to my experience)
  
Set the JAVA_HOME environment variable to the path of 
      the JDK
  
 Download Tomcat 6 from http://tomcat.apache.org/download-60.cgi
  
 Click on the downloaded setup.exe file
  
 Select Core+service+examples i.e. full install
  
 When the installer asks for the JRE, provide the path for jre 5 (jre 6 did not work for me)
  
 For user name and password I kept user name to be admin password to be blank [you can also set one]
  
 Next, Next, Finish - tomcat will be installed and start running [if the option was selected]
  
 Set the CATALINA_HOME environment variable to the installation path of the Tomcat 6.0 - it is important for deploying J2EE web applications under Tomcat



Web Hosting Companies


Best Hosting Companies
I was searching for a suitable webhosting for me. Until now features and cost wise I liked HostGator, VodaHost, HostMonster, BlueHost. Yahoo is another one I like but pricy. I am into hostgator and vodahost mainly. Though, vodahost has some bad reputation and their customer support may not be great. Just few other hosting companies are below. They are also very popular with huge customers. They may be better than Hostgator or Vodahost or HostMonster for you but for me I am sticking with HostGator[Do not have much experience with their customer support though]. It's really difficult to come up with the best.

	GoDaddy.com

	
Dotster.com

        
Lunar Pages

        
 Easy CGI

	
1 & 1 Hosting

	
HostGator

        
An Hosting

        
HostRocket.Com


	
Netfirms

	
FatCow 

	
techhosting.com



Choosing the best video format for your web site



  

      Choosing the best video format for your web site
  


Complete path analysis to get a merchant account


Please Check:

http://www.sitepoint.com/article/merchant-account-review


Detail Discussion to have a Merchant account


If pricing is a concern check it.
http://www.sitepoint.com/article/money-where-mouse-is-gateways/4


For detail explanations, please check the following link:
http://www.sitepoint.com/article/money-where-mouse-is-gateways



Online Payment Processing with Moneris



Resources
Video Tutorial on Payment Processing by JustEtc

 Guide on How to implement: https://www3.moneris.com/connect/en/download/feb05/HOSTED/eSELECTplus_HPP_IG.pdf
 Demo for Hosted Pay Page Implementation:  https://www3.moneris.com/connect/en/process/tryit/index.html
 Demo Store Administration: https://esqa.moneris.com/mpg/admin/hppv3_config/index.php



Topics Covered

 Collect Order Information: Basic, Detail
 Go to Moneris Paypage : Validate payment, Configure payment screen 
 Return from Moneris: Success: Show success message & Receipt, Failure: Show failure message
Administer Moneris Store: Customize pay page appearance, 
Response Field Configuration, Success & Failure page configuration




Search Engines To Submit your Online Stores


 

                     
                      Search Engines
                      
                    
                     
                      Robots (Search Engines)(Major)

                         Make sure and submit to these. 
 
 Aeiwi 
                        
 Alexa 
                        
 AltaVista 
                        
 AOL 
                        Netfind 
 Anzwers 
                        
 Canada.com 
                        
 Direct 
                        Hit 
 EuroSeek 
                        
 Excite 
                        
 Find 
                        What 
 Google 
                        
 HotBot 
                        
 ICQ 
                        It 
 I 
                        Won 
 InfoMak 
                        
 InfoSeek 
                        
 Lycos 
                        
 MSN 
                        Search 
 Northern 
                        Light 
 NBCi 
                        
 Surf 
                        Gopher 
 Thunderstone 
                        
 UKMax 
                        
 WebCrawler 
                        
 World 
                        Search Center 
 What-U-Seek 
                        
 
 

                        Indexes & Catalogs (Major)

                         Submit to these critical directories manually 
                        so nothing is left to chance. 
 
 Britannica 
                        
 LookSmart 
                        
 ComFind 
                        
 Jayde 
                        
 LookSmart 
                        
 Lycos 
                        (directory)  
 Netscape 
                        Search 
 Open 
                        Directory Project 
 Pronet 
                        
 Rex 
                        
 Snap! 
                        
 TurnPike 
                        
 What's 
                        New Too 
 Yahoo 
                        
 Yellow 
                        Pages 

                        

                        

                        Robots (Smaller Search Engines)

                        

                        A2Z 
                        Solutions 
 Diabolos 
                        
 Fathead 
                        
 Final 
                        Search 
 Funky 
                        Cat 
 Galaxy 
                        
 GlobeTech 
                        
 Matilda 
                        
 MaxBan 
                        
 National 
                        Directory  
 Neftem 
                        
 NetSearch 
                        
 Search 
                        It 
 The 
                        Cozy Cabin 
 Web 
                        Search 2K 
 WhatUseek 
                        
 World 
                        Search Center 
 
 

                        Indexes & Catalogs (General)

                        

                        ABAT NZ 
 CanLinks 
                        
 CyberDirectory 
                        
 Dewa 
                        
 Discover 
                        it 
 DirectFind 
                        
 EarthFind 
                        
 EgyptWeb 
                        
 ELaud 
                        
 FetchDog 
                        
 Find 
                        It 
 FindLink 
                        
 Frequent 
                        Finders 
 Global 
                        Page 
 http://www.gohip.com/ 
                        
 HandiLinks 
                        
 Hits 
                        Galore 
 ICN 
                        iExplorer 
 Infohiway 
                        
 InfoSpace 
                        
 JumpCity 
                        
 LifeStyle 
                        UK 
 LinkMaster 
                        
 MasterSite 
                        
 NerdWorld 
                        
 NTT 
                        Directory 
 Omnisearch 
                        
 PeekABoo 
                        
 PlanetClick 
                        
 PointGuide 
                        
 QuestFinder 
                        
 Scrub 
                        The Web 
 SearchBlazer 
                        
 SearchHound 
                        
 SearchKing 
                        
 SearchMode 
                        
 SelectSurf 
                        
 SiteShack 
                        
 SplatSearch 
                        
 Starting 
                        Point 
 theNet1 
                        
 WebIndex 
                        
 WebScout 
                        
 WebSleuth 
                        
 WhatsNu 
                        
 WebVenture 
                        Hotlist 
 Yep 
                        
 
 

                        Indexes & Catalogs (General Business Related)

                        

                        411Locate 
 411Now 
                        
 AE 
                        Business Exchange 
 BizCardz 
                        
 BizWeb 
                        
 Business 
                        Seek 
 Comfind 
                        
 InfoMarket 
                        
 LinkStar 
                        
 OZOnline 
                        
 ProNet 
                        
 QuickPage 
                        
 WebDirect 
                        
 USA 
                        Online 
                    
                     
                       
                    
                     
                      
                    
                  
 

Required Components for Internet Income





				Do you want to earn through your website? Well you want to start your own home business. In this category, we will provide you detailed information to meet your needs. We will provide information how you can earn through your website. We will also explore the opportunities for online based home business and online business.

				 First you need to know what are the options that can make you money through your websites. If you search the Internet you will find thousands of options and opportunities. I personally believe all of them are not useful. Some of them are just scam. We will try to identify some good options.

				 Here we will discuss our opinions in several steps: Steps:

				

					 Types of programs that will pay you
                  
 Requirements and tools needed for such programs
      
				                                            
				                                             Types of Programs. For details click on HOME Button.


				                                            

				                                               Pay Per Click
					                                          
 Pay Per Surf
					                                          
 Pay Per Sale
					                                          
 Pay Per Lead
					                                          
 Pay Per Email Read
					                                          
 Pay Per Pop Up show
					                                          
 Pay for Blind Clicks
					                                          
 Earn by Joining Reseller Programs
					                                          
 Being a Seller in a Program
				                                            

				                                            Well, these are some basic categories. We will add when we are familiar with new options. You can join and test one program alone. Even, you can try multiple programs simultaneously. Please, check the policies for corresponding programs whether they comply together.
				                                            
				                                             Tools and Requirements needed for online earning:

				                                            

				                                               A Well Designed Website
					                                          
 Website Hosted with User Friendly URL
					                                          
 Merchant Tools
					                                          
 Marketting
				                                            

				                                            
				                                             A Well Designed Website

				  You yourself can build your website or take help of an expert to build your website. You can learn HTML, FrontPage, DreamWeaver, JavaScript, Phtoshop, Flash, PHP, MySQL to build a good website. In future links to several free tools to build website will be provided. 
				                                             Website Hosted with User Friendly URL

				  You need a hosting space for your website. There are plenty of free webhosting services in the Internet. The good talk about them are they are free. However, they are not good for online business. Also they are not good for Pay Per Click programs as they might force you to keep their adds on your webpages. If you are interested with free webhosting please search google.com with the phrase "free webhosting" and try the links. You can also try the link http://www.free-webhosts.com/. If you want paid hosting service you can search google with the phrase "ranking web hosting". You can also try with similar phrases. You can also try www.TheHostingChart.com, www.top10webhosting.com, toptenreviews.com. 

				                                             For online transactions you will need to setup merchant accounts with your hosting packages. You need secure SSL connection. If you work as a seller you will need to use shopping cart from your hosting/other companies. You can yourself program your shopping cart. Verisign is a company that will help you to preserve security in your online transactions. 
				                                             When you join a program you will get payment from the company. The company will pay you in various ways. They might send you check. There are some convenient ways to accept money online from the owner of the programs. Such as:
				                                            

				                                               Paypal
						                                      
 Egold
						                                      
 StormPay
						                                      
 IntGold
						                                      
 EPassporte
				                                            

				                                            Personally I am familir with paypal. I found it to be secure and trustable way of making online transactions. Other options are new to me. However, not all companies work paypal. Hence, in some cases you will not have any option to avoid the others. Read articles regarding the other options, consult with your friends and other webmasters to know about the services clearly.
                                           
										   Meta Tag Generator




							               Websites that offers free Meta tag   Generator Utility
							               
                                             www.submitexpress.com

                                             
www.webwizguide.info 
      



20 Tips to Improve ASP.net Application Performance



Please check: http://www.realsoftwaredevelopment.com/2007/08/20-tips-to-impr.html


ASP.Net Controls



HTML Server Controls

HtmlAnchor

HtmlButton

HtmlForm

HtmlGeneric

HtmlImage

HtmlInputButton

HtmlInputCheckBox

HtmlInputFile

HtmlInputHidden

HtmlInputImage

HtmlInputRadioButton

HtmlInputText

HtmlSelect

HtmlTable

HtmlTableCell

HtmlTableRow

HtmlTextArea




Web Server Controls

AdRotator

Button

Calendar

CalendarDay

CheckBox

CheckBoxList

DataGrid

DataList

DropDownList

HyperLink

Image

ImageButton

Label

LinkButton

ListBox

ListItem

Literal

Panel

PlaceHolder

RadioButton

RadioButtonList

BulletedList

Repeater

Style

Table

TableCell

TableRow

TextBox

Xml




Validation Server Controls

CompareValidator

CustomValidator

RangeValidator

RegularExpressionValidator

RequiredFieldValidator

ValidationSummary




ASP.Net Examples


ASP.NET HTML Controls

HTMLAnchor

HTMLButton

HTMLImage

HTMLImage 2

HTMLInputbutton

HTMLInputCheckbox

HTMLInputHidden

HTMLInputImage

HTMLInputRadiobutton

HTMLTable

HTMLTable 2

HTMLTextarea


ASP.NET Web Controls

AdRotator

Button

Button 2

Calendar

Calendar 2

Calendar 3

Checkbox

CheckboxList

DataList

DataList with styles

DataList with 

DropdownList

Hyperlink

Image

ImageButton

Label

LinkButton

Listbox

Literal

Literal 2

Panel

Radiobutton

RadiobuttonList

Repeater

Repeater with 

Repeater with 

Table

Table 2

Textbox

Textbox 2

Textbox 3

XML



ASP.NET Validation Controls

CompareValidator

CompareValidator 2

CustomValidator

RangeValidator

RangeValidator 2

RegularExpressionValidator

RequiredFieldValidator

Validationsummary

Validationsummary 2


ASP.NET Events

Page_Load

Page.IsPostBack


ASP.NET Data Binding

ArrayList RadioButtonList

ArrayList DropDownList

Hashtable RadioButtonList 1

Hashtable RadiobuttonList 2

Hashtable DropDownList

SortedList RadioButtonList 1

SortedList RadiobuttonList 2

SortedList DropDownList

XML RadiobuttonList


ASP.NET Database
Database connection - Bind to a Repeater control

Database connection - Bind to a DataList control




How to optimize SQL Server Cursors



Optimize Cursors

 Avoid using SQL Server cursors whenever possible
 Always close SQL Server cursors when result sets are not needed
 Deallocate SQL Server cursors when the data structures comprising the cursors are not needed
 Reduce the number of records to process in the cursor
 Only use the required columns in the cursors 
 Use READ ONLY cursors, whenever possible, instead of updatable cursors.
 Avoid using insensitive, static and keyset cursors, whenever possible.
 Use FAST_FORWARD cursors, whenever possible.
 Use FORWARD_ONLY cursors, if you need updatable cursors 




What are cursors?



Cursors are server side database objects that are used by 
applications to apply operations on the database table data 
on a row-by-row basis. The operations may vary from one row 
to another row dynamically based on the requirements 
(business logic) and also multiple operations can be 
performed on the same row. Typical SQL commands apply the 
same updates/changes to all the selected rows at once where 
cursors apply updates/changes one by one row. 

Cursors must be declared in the database before they can be 
used/called from the applications [front end]. Afterwards, 
you can open cursors to fetch data using them, you can fetch
row by row and make multiple operations on the currently 
active row in the cursor. You should close the cursors and 
deallocate them after you are done with the cursors.


This is the Transact-SQL Extended Syntax:

DECLARE cursor_name CURSOR
[LOCAL | GLOBAL]
[FORWARD_ONLY | SCROLL]
[STATIC | KEYSET | DYNAMIC | FAST_FORWARD]
[READ_ONLY | SCROLL_LOCKS | OPTIMISTIC]
[TYPE_WARNING]
FOR select_statement
[FOR UPDATE [OF column_name [,...n]]]

An example cursor:

DECLARE AuthorsCursor CURSOR FOR
SELECT authors.id, au_lname, au_fname
FROM authors
ORDER BY authors.id

Another Example

DECLARE @AuthorID char(11)
	
DECLARE Cursor1 CURSOR READ_ONLY
FOR
SELECT au_id
FROM authors

OPEN Cursor1

FETCH NEXT FROM Cursor1
INTO @AuthorID

WHILE @@FETCH_STATUS = 0
BEGIN

	PRINT @AuthorID

	FETCH NEXT FROM Cursor1
	INTO @AuthorID

END

CLOSE Cursor1
DEALLOCATE Cursor1


where

cursor_name: The name of the server side cursor

LOCAL: The cursor will be available only to the batch, stored procedure, or trigger in which the cursor was created 

GLOBAL: The cursor is global to the connection 

FORWARD_ONLY: The cursor can only fetch data sequentially 

STATIC: The cursor will use a temporary copy of the data instead of base tables 

KEYSET: Specifies keysets so that the membership and order of rows in the cursor are fixed when the cursor is opened 

DYNAMIC: The cursor reflects all data changes made to the base tables as you scroll around the cursor 

FAST_FORWARD: The cursor is FORWARD_ONLY and READ_ONLY  

READ ONLY: The cursor [data] cannot be updated

SCROLL_LOCKS: The fetched data will be locked 

OPTIMISTIC: The cursor does not lock rows as they are read into the cursor 

select_statement: The standard select statement, cannot contain COMPUTE, COMPUTE BY, FOR BROWSE, and INTO keywords

UPDATE [OF column_name [,...n]]: Specifies which columns can be updated






SQL Server Hints



SQL Server Hints
----------------
What are hints?
Simply to influence query execution plans to retrieve data 
faster.

syscacheobjects
----------------
SQL server after compiling a query creates the execution 
plan and keeps it on syscacheobjects object.
You can query the object to see the existing query plans as 
follows:

select * from sys.syscacheobjects
where cacheobjtype='compiled plan'


Hints
-----

When you specify hints in your queries the query execution 
plans are biased toward your hints rather than using default
 strategies.

Types of Hints
--------------
Join Hints: Affects the joins [join types]
Query Hints: Affects overall execution plan
Table: Affects to table access 


Join Hints
----------
Loops: Uses nesting for join. Each row of the inner table is
 checked for condition satisfaction with the corresponding 
outer row.
Hash: One table is treated as a hash table and the other is 
scanned one row at a time and the hash function is used to 
find equalities

Merge: Each table is sorted first. Then they are compared 
row by row [corresponding]

Remote: In this case, at least one table is remote. The join
 is done at the right table side.


Example:

select *
-----
----
---
option (merge join)


or

select * 
from x
inner merge join y on...


Query Hints:
------------
Specified at the end of the query with keyword 'Option'


select * from x
------------
------------
option (recompile, fast 80)
Hash Group or Order groups:  Aggregations (group by, compute, distinct) are done by hashing or ordering
Concat Union, Hash Union, Merge Union: All unions will be done with the specified union type
Loop Join, Hash Join, Merge Join: Joins will be done with the specified join types
FAST number_rows:
Force Order:
MaxDop:
Optimize For:
Recompile:
Keep Plan:
Expand Views:



Table Hints:
------------
Affects how the table will be locked or which index will be 
used for the query.
NoEXPAND
INDEX
fastfirstrow
nowait
rowlockpaglock
tablock
nolock
holdlock
ignore_triggers


Plan Guides
-----------
Sometimes queries are originated from a third part application and you have no control to change the query.
You can use plan guides to influence such queries. For example: Using plan guides you can specify the nature of the
 select, update, insert queries.
You can use built in stored procedures to create or drop 
plan guides.

sp_create_plan_guide
sp_control_plan_guide
















Scalability: SQL Server 2005



Scalability: SQL Server 2005



After you have optimized your database design and the application design, you can improve the scalability of SQL Server in two ways

1.Scaling Up

2.Scaling Out



Scaling Up: Improve performance by 

1. Adding more processors, memory, and storage capacity


2. Replacing existing hardware with faster hardware


Note: You also need the right version of SQL Server so that scaling up is supported.



How to scale up Processors: 

SQL Server is mostly I/O bound not CPU bound, still better/faster CPU usually provides better performance [depends on the application need though].


Processor choices:
32 bit 

64 bit x64

64 bit IA64

Hyperthread technology

Multiprocessor based server

Multicore based servers



It is always better to go for 64 bit than 32 bit as it will also support more memory. 64 bit x64 processors provide better performance than ia64 however if your work requires lots of floating point operations and the workload needs > 8 processors you can think about IA64 processors



Multiple processor systems provide better performance than the single processor systems. Windows implements SMP architecture of parallel computing and SQL Server 2005 also takes advantage of it.



Multiple processor systems usually performs better than the equivalent multicore uniprocessor systems.



Intel's hyperthreading technology may increase performance (10-20%) based on the applications (but not always)




Memory Subsystem:

As SQL server is I/O bound using more memory almost always increases performance.  Though the amount of memory  that we can add depends on the operating systems. 32 bit operating systems supports 4GB RAM max. For 32 bit windows 2 GB is reserved for operating system, in Windows Server 2003 we can specify 1 gb for operating system so getting 3gb for SQL Server.



32 bit SQL Servers can address 4 gb ram, the actual ram amount depends on the operating system used. if 32 bit windows then 2 to 3 gb max as mentioned before



When 64 bit windows and 64 bit sql server then physical memory limits 32TB.



I/O SubSystems:

You can improve disk I/O subsystem by using an appropriate RAID array or SAN (Storage Area Network) solution



Using Network Interface Card (NIC) teaming, you can also improve performance. NIC teaming allows to bond multiple physical NICs into one logical network device. Teaming provides load balance, fault tolerance, and high bandwidth.



Scaling Out will be discussed later.


Scaling Out involves using multiple SQL servers to provide increased scalability.




Scaling Out



Methods


  SQL Server instances
 
 Clustering
 
 Database mirroring
 
 Log shipping
 
 Replication
 
 Shared scalable databases



 SQL Server instances
In the same computer install multiple instance of SQL Server to take advantage of multiple processors. Each instance may use separate processor with separate lock manager, worker threads, tempdb system database. 



 Clustering
Failover Clustering can provide robustness and protection against failure. Clustering can provide scaling using spare hardware through passive nodes



 
 Database mirroring
With database mirroring transaction logs are directly sent to the mirror. The mirror is up to date and can be used in case of failure of the principle server. 



 Log shipping
It depends on the transaction log backups, file copying. The secondary database need not to be updated in real time. The secondary database is read only and hence, be in great use for reporting purposes. 



 Replication
Merge Replication: Both way, both from and to publishers and subscribers

Transactional Replication: Publisher to the subscriber


 Shared scalable databases
Scale out a read-only database only for reporting purposes.


Dynamic Management Views



Dynamic Management Views provide ways to analyze database performance and to find the cause behind bad-performing SQL server databases/instances. Bad performance can be due to: poor design, insufficient memory, poorly configured system, disk bottlenecks, poorly written queries and many others



Previously Windows System Monitor(perfmon.exe) and SQL server profiler were used to find the cause of bad-performance. Now, Dynamic Management Views can help a lot better. 



Dynamic Management Views are categorized into 12 categories



   Common language runtime:
  
 Database: Provides details about database sizes, files used, and partition information.
  
 Database mirroring related: About mirroring and mirroed databases
  
 Execution related: Provides insight into query execution statistics.
  
 Full text search: Provides information on full-text catalogs, indexes, full-text crawl memory buffer
 
 Input/Output Related: Provides insights into I/O operations, I/O devices, and database file statistics.
 
 Index related: Database file statistics
 
 Query notification related: Insights into active query notifications subscriptions in the server 
 
 Replication related: Insights into the workings of replication in the database
 
Service Broker Related: Insights into the workings of Service Broker
 Sql server operating system related: Insights into the internal operations of the SQL Server OS.
 Transaction Related: Insights into the operations of active transactions




Performance Data Warehouse: A historical archive of periodic snapshots of the DMV data of interest. How can it help? the problem may occur only at night 3:00 a.m. and when there are not many users. If you want to fix the issue in the morning Performance Data Warehouse will be of great help. 







SQL Server Database System Tuning



Database tuning approach


   Proactive approach
  
 Reactive approach

Best Approach: Use a mix of both.



Be aware (collect information) of the followings that may have significant impact on the performance. 


Hardware: Server, Available memory, number of processors, disk subsystems. 



Network Infrastructure: Network Cards, Switches, and the rest of your LAN and WAN. 



Operating System: Make sure the OpSys is optimally configured for SQL Server. 



Database Engine: Know about the SQL Server Architecture and about your operational environments. 



Database: Tune database properly 



Client Connection: How clients connect to the server 



Monitoring and Tuning Hardware: Use Network Monitor Agent, Performance Logs and Alerts, System Monitor, and Task Manager. 



System monitor (perfmon.exe) is a great tool for the purpose Using perfmon.exe you can also find where the bottleneck is Processor Subsystem, Memory Subsystem, I/O Subsystem 



Monitoring and Tuning SQL Server:
Tools:

  DBCC Commands
 
 Dynamic Management Views
 
 SQL Server Profiler
 
 SQL Server Management Studio
 
 System Stored Procedures
 
 SQL Trace


System Monitor: when SQL server is installed many new parameters (performance objects and their counters) are added to System Monitor (perfmon.exe) that help to monitor SQL Server performance.



SQL Server Profiler: This tool is used to capture traces like client activities, stored procedure calls, lock activities. SQL server profiler can help to determine if the  client application is at fault. 



SQL Trace: create traces using using stored procedures.





Tuning the tempdb system database



   Capacity plan and pre-allocate adequate space
  
 Separate the log file from the database file
  
 Use multiple secondary files for the tempDB system database
 
 Use a faster disk
 
 Use an appropriate RAID solution.
 
 Use local disk sybsystem for tempdb.


Tuning Database Layout



Use file and filegroup architecture properly.

File: Use multiple data files for your databases.



Filegroups:
example: create two file groups and place them in different drives. Create tables in one file group and create non-clustered indexes in the other. table I/O and Index I/O are now divided.





SQL Server: Index



SQL Server: Index





 Indexes make database access faster. Without index your queries will run but indexes can increase the performance dramatically.

 You can define multiple indexes for a table and select the index that is required for current operations.

 Only one clustered index is supported for a table

 To get advantage of indexes you have to mention the index related constraints in your where clause like where last_name ='xyz'

 If you have indexes on two or more columns, in where clause mention the first column name/constraint first [that was first in the index creation].

 A clustered index contains table data sorted in the index where a non-clustered index contains reference to the table data or clustered index. Non-clustered indexes are both physically and logically independent of table data.



Index Best Practices 



 Select a column/(columns) for indexes that will provide good uniqueness and selectivity otherwise indexing may degrade the performance

 Create indexes that result in lower number of rows to be searched 

 Create indexes that select a range of rows

 Try to create clustered index with as uniqueness as possible

 Keep indexes as narrow as possible (not many/unnecessary columns)

 Don't index very small table






In SQL server, you can create indexes through your sql statements or using the development studio interface.




SQL Server : Backups



Why are backups needed? 


To protect accidental data loss. Still, if you use highly available and fault-tolerant systems like SAN, and RAID, you may need to backup your database regularly. These fault tolerant systems can not provide accidental data delete by users, accidental data corruption from software and hardware failure. If you have a disaster recovery site or a secondary datacenter to where all data are replicated and data changes are stored, then you may not need backup but otherwise regular backups are always useful.



Data backup can restore data until the last backup. . Transaction Logs may help to restore data up to the point of failure. Restore data from the data backup, then if you have the transaction log up to the failure apply it to the data.



SQL Server Recovery Models:



 Simple Recovery Model. Transaction logs are not used
 Full Recovery Model: Use both data and transaction log backups
Bulk-logged recovery model: Like full recovery model. But here bulk operations are minimally logged to the transaction log. So full recovery becomes faster.


Types of Backups


    Full database backup: Full database, all files and file groups are backed up
   
 Partial Back up:  It's not the differential backup. Here, all primary file groups and any other file groups that are read-write are backed up. But read-only file groups are not backed up by default. 
   
 File or file group backup: Usefull when full back ups take too long. Backup in parts. 
  
Differential back up: Backup only the changes. Should be applied to a full backup.
  
Log backup: In log back ups, transaction logs are backed up regularly. It helps in bulk logged recovery model and full recovery model.
 
Copy only backups:
 
 Full text catalog backups




Knowing about backup devices, media sets, and backup history  tables is also important.


Mirrored Media Sets: Backup data to more than one media at the same  time.



Backup Strategy:


Based on your company need and type of data, you should come up with a backup strategy.




Some backup strategies


Strategy - 1


  Take full database backup every saturday night
 
 Take a differential backup every wednesday night
 
 Perform, continual transaction log backups every 30 minutes


Strategy - 2: If the database is too big, and user activities need continuous uptime and optimal performance


  Filegroup 1 backup every saturday night
 
 Filegroup 2 backup every sunday night
 
 File group 1 differential backup every Tuesday night
 
 File group 2 differential backup every wednesday night
 
 File group 1 differential backup every Thursday night
 
 File group 2 differential backup every Friday night
 
 Perform, continual transaction log backups every 30 minutes



Backup System Databases 


It is also important to back up system databases like master, model, msdb, tempdb, distribution, resource.



Differences between Java Bean and EJB



please check

http://members.tripod.com/gsraj/ejb/chapter/






A good book on EJB







Opening and reading files with Java JDK 1.0.x



   1. Open the file with the File class;
   2. Create a FileInputStream object using the File object;
   3. Convert the FileInputStream to a BufferedInputStream to greatly increase file reading speed;
   4. Convert the BufferedInputStream to a DataInputStream; the methods of DataInputStream give me a fair amount of flexibility in reading the data.
   5. Read the file until the end


File f = new File("mydata.txt"); 
FileInputStream fis = new FileInputStream(f); 
BufferedInputStream bis = new BufferedInputStream(fis); 
DataInputStream dis = new DataInputStream(bis);  
String record = null; 

try { 

   while ( (record=dis.readLine()) != null ) { 
      // 
      // put your logic here to work with "record" 
      // 
   } 

} catch (IOException e) { 
   // 
   // put your error-handling code here 
   // 
} 



Java XML Example - XML File Parse and Use Attributes



A good example: http://developerlife.com/tutorials/?p=25 

Another very good example: http://www.developerfusion.co.uk/show/2064/: I followed this code to extract attribute values from an xml file. 


MVC : Struts : Java : Industry Web Application



Industries use frameworks for application development quite often. 

For example: Java concepts like JSP, Servlet, Swing, Bean, JDBC can 

be used directly to create web-applications but when such 

applications become big, it becomes difficult to maintain and 

develop them further. Hence, frameworks like struts are used to develop 

large web-based Java applications. This makes maintenance and 

further development easier. If you need to write a very simple web 

application with a few pages, then you might consider using 

JSP/Servlet directly otherwise Struts like frameworks are better 

options.

Struts-1 uses the concept Model View Architecture (MVC) and provides 

the controller. In MVC model, Model represents business logic, View 
represents user interfaces, and Controller represents/controls control 
flow of the application. 


Struts' control layer is based on standard technologies like 

Java Servlets, JavaBeans, ResourceBundles, and XML, as well as 

various Apache Commons  packages, like BeanUtils and Chain of 

Responsibility. 

For the Model,  struts-1 framework can interact with standard 
data access technologies, like JDBC  and EJB,  as well as most 
any third-party packages, like Hibernate,  iBATIS,  or Object Relational 
Bridge.  For the View,  the framework works well with JavaServer Pages,  
including JSTL and JSF,  as well as  Velocity Templates,  XSLT,  and 
other presentation systems.


The framework's Controller acts as a bridge between the application's Model and the web View. 
When a request is received, the Controller invokes an Action  class. The Action class consults 
with the Model to examine or update the application's state. The framework provides an ActionForm  
class to help transfer data between Model and View.

Struts-1 Configuration
-----------------------
web.xml is one of the configuration files. It is an XML-formatted file that works as a 
deployment descriptor. 

struts-config.xml is another resource file to initialize the applications resources. 
These resources include  ActionForms  to collect input from users,  ActionMappings  
to direct input to server-side  Actions,  and ActionForwards to select output pages.

Sample struts-config.xml file.

<?xml version="1.0" encoding="ISO-8859-1" ?>
    <!DOCTYPE struts-config PUBLIC
          "-//Apache Software Foundation//DTD Struts Configuration 1.3//EN"
          "http://struts.apache.org/dtds/struts-config_1_3.dtd">
    <struts-config>
        <form-beans>
            <form-bean
                name="logonForm"
                type="app.LogonForm"/>
        </form-beans>
        <action-mappings>
            <action
                path="/Welcome"
                forward="/pages/Welcome.jsp"/>
            <action
                path="/Logon"
                forward="/pages/Logon.jsp"/>
            <action
                path="/LogonSubmit"
                type="app.LogonAction"
                name="logonForm"
                scope="request"
                validate="true"
                input="/pages/Logon.jsp">
                <forward
                    name="success"
                    path="/pages/Welcome.jsp"/>
                <forward
                    name="failure"
                    path="/pages/Logon.jsp"/>
            </action>
            <action
                path="/Logoff"
                type="app.LogoffAction">
                <forward
                    name="success"
                    path="/pages/Logoff.jsp"/>
            </action>
        </action-mappings>
        <message-resources parameter="resources.application"/>
    </struts-config>

Other resources like Validators can be initialized here.




Linked List and Iterator in Java



/*
 * LinkedList.java
 *
 * Created on January 10, 2008, 8:51 PM
 *
 * To change this template, choose Tools | Template Manager
 * and open the template in the editor.
 */

package linkedlist;

import java.util.List;
import java.util.LinkedList;
import java.util.Iterator;
import java.util.ListIterator;
import java.util.Collections;
import java.util.Random;

/**
 *
 * @author Sayed
 */
public class LinkedListTest {
    
    /** Creates a new instance of LinkedList */
    public LinkedListTest() {
    }
    
    /**
     *Example operations using linked lists
     */
    
    public void linkedListOperation(){
        
        final int MAX = 10;
        int counter = 0;

        //create two linked lists
        List listA = new LinkedList();
        List listB = new LinkedList();

        //store data in the linked list A
        for (int i = 0; i < MAX; i++) {
            System.out.println("  - Storing Integer(" + i + ")");
            listA.add(new Integer(i));
        }
       
        //print data from the linked list using iterator 
        Iterator it = listA.iterator();
        while (it.hasNext()) {
            System.out.println(it.next());
        }

        //print data from the linked list using listIterator. 
        counter = 0;
        ListIterator liIt = listA.listIterator();
        while (liIt.hasNext()) {
            System.out.println("Element [" + counter + "] = " + liIt.next());
            System.out.println("  - hasPrevious    = " + liIt.hasPrevious());
            System.out.println("  - hasNext        = " + liIt.hasNext());
            System.out.println("  - previousIndex  = " + liIt.previousIndex());
            System.out.println("  - nextIndex      = " + liIt.nextIndex());
            System.out.println();
            counter++;
        }


        //retrieve data from the linked list using index
        for (int j=0; j < listA.size(); j++) {
            System.out.println("[" + j + "] - " + listA.get(j));
        }

        //find the location of an element
        int locationIndex = listA.indexOf("5");
        System.out.println("Index location of the String \"5\" is: " + locationIndex);  

        //find the first and the last location of an element
        System.out.println("First occurance search for String \"5\".  Index =  " + listA.indexOf("5"));
        System.out.println("Last Index search for String \"5\".       Index =  " + listA.lastIndexOf("5"));

        //create a sublist from the list 
        List listSub = listA.subList(10, listA.size());
        System.out.println("New Sub-List from index 10 to " + listA.size() + ": " + listSub);

        //sort the sub-list
        System.out.println("Original List   : " + listSub);
        Collections.sort(listSub);
        System.out.println("New Sorted List : " + listSub);
        System.out.println();

        //reverse the new sub-list
        System.out.println("Original List     : " + listSub);
        Collections.reverse(listSub);
        System.out.println("New Reversed List : " + listSub);
        System.out.println();

        //check to see if the lists are empty
        System.out.println("Is List A empty?   " + listA.isEmpty());
        System.out.println("Is List B empty?   " + listB.isEmpty());
        System.out.println("Is Sub-List empty? " + listSub.isEmpty());
        
        //compare two lists
        System.out.println("A=B? " + listA.equals(listB));        
        System.out.println();

        //Shuffle the elements around in some Random order for List A
        Collections.shuffle(listA, new Random());

        //convert a list into an array
        Object[] objArray = listA.toArray();
        for (int j=0; j < objArray.length; j++) {
            System.out.println("Array Element [" + j + "] = " + objArray[j]);
        }

        //clear listA
        System.out.println("List A   (before) : " + listA);        
        System.out.println();
        listA.clear();
        System.out.println("List A   (after)  : " + listA);        
        System.out.println();
        
    }
    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {
        // TODO code application logic here
        LinkedListTest listExample = new LinkedListTest();
        listExample.linkedListOperation();
    }
    
}





Set, TreeSet, Iterator in Java



/*
 * TreeSetExample.java
 *
 *Illustrates mathematical set operations
 *
 * Created on January 10, 2008, 9:28 PM
 *
 * To change this template, choose Tools | Template Manager
 * and open the template in the editor.
 */

package treesetexample;
import java.util.Set;
import java.util.TreeSet;
import java.util.Iterator;

/**
 *
 * @author Sayed
 */

public class TreeSetExample {
    
    /** Creates a new instance of TreeSetExample */
    public TreeSetExample() {
    }
    
    //example set operations 
     public static void treeSetOperations() {

        final int MAXIMUM = 20;

        //create a TreeSet
        Set ss = new TreeSet();

        //store data in the set, set can contain only one type of data
        for (int i = 0; i < MAXIMUM; i++) {
            System.out.println("  - Storing Data(" + i + ")");
            ss.add(new Integer(i));
        }

        //display set data using an iterator
        Iterator it = ss.iterator();
        while (it.hasNext()) {
            System.out.println(it.next());
        }
    }

        
    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {
        // TODO code application logic here
        TreeSetExample treeSet = new TreeSetExample();
        treeSet.treeSetOperations();
    }
    
}



Java Bean : Basic Idea



What is Java bean?
Just a component technology. You can create platform independent components using Java beans. 

Key Bean Concepts:

1. introspection: Through introspection beans expose their properties, methods, and events. Beans support 
introspection in two ways:
   1.1: Design patterns: The Introspector class examines beans for design patterns to discover bean features

   1.2: Through a related bean information class that implements the BeanInfo interface. The class lists the 
bean features that are to be exposed 

2. Properties: Are the appearance and behavior characteristics of a bean that can be changed at 
design time

3. Beans use events to communicate with other beans

4. Persistence enables beans to store and retrieve their state using serialization

5. Beans provide methods that can be called from other beans, or scripting language


Bean Property Types
--------------------

# Simple � with a single value 

# Indexed � a range of values 

# Bound � a change to the property results in a 
notification being sent to some other bean

# Constrained � a change to the property requries 
validation by other bean


Bean Properties can be
    *Writable � can be changed
          o Standard
          o Expert
          o Preferred 
    * Read Only � cannot be changed
    * Hidden � can be changed. not disclosed with the BeanInfo class 



How to upload data from an excel file to database using servlets?



Use third party API bundles like jexcelApi. 
http://jexcelapi.sourceforge.net/.


---

create an XML file to define the structure of your excel file like how many columns, column names, corresponding database table/class column/variable name, 



Create a Java class that can retrieve information from that xml file. You can use XPATH and DOM for the purpose. check http://www.ibm.com/developerworks/library/x-javaxpathapi.html for ideas



---


write an html form that use input type='file', the form action should point to the servlet that will collect data from the excel file and store it in the database. servlet will collect data from the input stream



-----------


in the servlet use the class that represents the xml file. to get information about the file that will help mapping the excel file data to the corresponding table column. You can also create a class representing the database table. From servlet extract data, create an object of table class type, and create a function that takes the object and inserts into the table.



---------------



How servlet will process the excel file:




jexcelAPI Workbook class represents the total workbook

use getsheet method of workbook class to get the sheet 
number 0,1,2....


use getCell method of worksheet to get a particular cell object in the excel file

use getContents on the cell object to get data in string type.



from the XML file having excel file structure, you can get number of columns in the file. So you can write a look that will read data row,column wise from the excel file



----

code to process excel file [in servlet]


 Workbook workbook = Workbook.getWorkbook(new File("myfile.xls"));


 Sheet sheet = workbook.getSheet(0);


 Cell a1 = sheet.getCell(0,0);


Cell b2 = sheet.getCell(1,1);


Cell c2 = sheet.getCell(2,1);



String stringa1 = a1.getContents();


String stringb2 = b2.getContents();


String stringc2 = c2.getContents();



----------------------


check the following webpage, it provides file upload and extract data from input stream in servlet applications





http://jexcelapi.sourceforge.net/resources/faq/






Java Collections Framework



Some URLs  

http://www.javaworld.com/javaworld/jw-11-1998/jw-11-collections.html?page=2

http://www.informit.com/articles/article.aspx?p=781700


http://java.sun.com/docs/books/tutorial/collections/index.html


Vector Vs. ArrayList 


Vector vs. Hashtable 


ArrayList vs. LinkedList 





Unit Testing in Eclipse for Java



Unit Testing in Eclipse for Java: just an overview 



Why Unit Test?


Say, you have written some Java classes, before making use of them in real application functionalities, it's always better to check whether the classes (their functions/methods) are working properly. Unit tests simply test a single unit like a single class, or a single function at a time. It's almost always a good practice to design the software first, also design the classes and their methods along with interactions among classes, early in the project. After, classes and their methods are written, you should do some testing to make sure they are working properly.



How to Unit test in Eclipse? 



1. You need to add junit.jar in your project build path. You can do that by selecting the project, then right click, then select properties, the java build path, then libraries tab, and then add jars/add external jars and select JUnit.jar.



2. You can create a folder to keep your unit test codes say unittestcodes.



3. The basic idea is, to test a class, you will need to create a test case class with methods like setUp, tearDown, and test methods for all the methods that you want to test (one for one). The setUp() method can be used to create the data for testing [you have to write the code though]. The other test methods will call the corresponding class methods using the data to check if the methods are working properly or not. Methods like assertTrue may come handy in the test methods. 



4. How to create these test classes and test methods? 


Right click the folder for testcode like unittestcodes, select new, select other, type Junit in the text box, select Junit test case...and then provide other parameters like the name of your test class, which class do you want to test, do you want to have setUp(), tearDown() methods or not?. In the next step, you have to select which methods of the class you want to test. Then the test class (skeleton) will be written for you. 



5. In the setUp() method, write code to build test data. From the other test methods call the related class methods to test them.



6. How to run the experiment: right click the name of this test class from the left window, select run as, select Junit test case.  Now analyze the output and fix the class methods if required. Try with different data, data from different ranges, boundary value data and you know what to test in your use cases. 








What is Spring Framework? What does it mean to J2EE developers



What is Spring Framework? What does it mean to J2EE developers?



Spring is a light-weight framework, very often referred as an alternative/competitor to EJB, for the development of enterprise-type applications. Spring provides many features such as declarative transaction management, access to  remote logic using RMI or web services, mailing facilities and database abstraction. 



Features of Spring Framework


  Transaction Management: A generic abstraction layer for transaction management that removes low-level interactions         

 JDBC Exception Handling: An  exception hierarchy to simplify the error handling strategy
       
 Integration with Hibernate, JDO, and iBATIS 
       
 AOP Framework: Aspect Oriented Programming Framework
         
 MVC Framework: Spring provides MVC web application framework built on core Spring functionality
 



Spring Architecture



   Spring AOP: Provides declarative enterprise services such as declarative transaction management
  
 Spring ORM: Provides integration layers for object-relational mapping APIs, including JDO, Hibernate and iBatis for database access.        
  
 Spring Web: Provides web application development stack that includes Spring MVC.
  
Spring DAO: Provides standardization to data access  using the technologies like JDBC, Hibernate or JDO.
  
 Spring Context: Provides support for using message sources, and resources. It is based on Java bean.
 
 Spring Web MVC: Provides MVC for web applications.
 
  Spring Core: Provides Dependency Injection features 


EJB 3: Stateless Bean




No need to maintain the state of a bean between calls. 

//CalculatorBean.java

@Stateless
public class CalculatorBean implements CalculatorRemote, CalculatorLocal
{
   public int add(int x, int y)
   {
      return x + y;
   }

   public int subtract(int x, int y)
   {
      return x - y;
   }
}


//CalculatorRemote.java
import javax.ejb.Remote;
@Remote
public interface CalculatorRemote extends Calculator
{

}


//CalculatorLocal.java 
import javax.ejb.Local;
@Local
public interface CalculatorLocal extends Calculator
{
}


//Client.java

import tutorial.stateless.bean.Calculator;
import tutorial.stateless.bean.CalculatorRemote;
import javax.naming.InitialContext;

public class Client
{
   public static void main(String[] args) throws Exception
   {
      InitialContext ctx = new InitialContext();
      Calculator calculator = (Calculator) ctx.lookup("CalculatorBean/remote");

      System.out.println("1 + 1 = " + calculator.add(1, 1));
      System.out.println("1 - 1 = " + calculator.subtract(1, 1));
   }
}




EJB 2: How to build a stateless EJB



EJB 2: How to build a stateless EJB

   Install an EJB Server
  
 Specify the EJB  Remote Interface
  
 Specify the Home Interface
  
 Write the EJB bean Class
  
 Create the ejb-jar File
  
 Deploy the EJB  bean
  
 Write the EJB Client
  
 Run the Client



EJB 3: Statefull EJB




States need to be maintained between calls. In EJB3 all beans are homeless [no home interface]

//ShoppingCartBean.java

import java.io.Serializable;
import java.util.HashMap;
import javax.ejb.Remove;
import javax.ejb.Stateful;
import javax.ejb.Remote;


@Stateful
@Remote(ShoppingCart.class)
public class ShoppingCartBean implements ShoppingCart, Serializable
{
   private HashMap cart = new HashMap();

   public void buy(String product, int quantity)
   {
      if (cart.containsKey(product))
      {
         int currq = cart.get(product);
         currq += quantity;
         cart.put(product, currq);
      }
      else
      {
         cart.put(product, quantity);
      }
   }

   public HashMap getCartContents()
   {
      return cart;
   }

   @Remove
   public void checkout()
   {
      System.out.println("To be implemented");
   }
}


//ShoppingCart.java
//remote interface
import java.util.HashMap;
import javax.ejb.Remove;

public interface ShoppingCart
{
   void buy(String product, int quantity);

   HashMap getCartContents();

   @Remove void checkout();
}


//client
//Client.java
//client uses JNDI to look up for EJB services

import java.util.HashMap;
import javax.naming.InitialContext;
import org.jboss.tutorial.stateful.bean.ShoppingCart;


public class Client
{
   public static void main(String[] args) throws Exception
   {
      InitialContext ctx = new InitialContext();
      ShoppingCart cart = (ShoppingCart) ctx.lookup("ShoppingCartBean/remote");

      System.out.println("Buying 1 memory stick");
      cart.buy("Memory stick", 1);
      System.out.println("Buying another memory stick");
      cart.buy("Memory stick", 1);

      System.out.println("Buying a laptop");
      cart.buy("Laptop", 1);

      System.out.println("Print cart:");
      HashMap fullCart = cart.getCartContents();
      for (String product : fullCart.keySet())
      {
         System.out.println(fullCart.get(product) + "     " + product);
      }

      System.out.println("Checkout");
      cart.checkout();

      System.out.println("Should throw an object not found exception by invoking on cart after @Remove method");
      try
      {
         cart.getCartContents();
      }
      catch (javax.ejb.EJBNoSuchObjectException e)
      {
         System.out.println("Successfully caught no such object exception.");
      }


   }
}



EJB 3: Entity Bean Basic



Plain Java objects with persistence storage. They are not 
remotable and must be accessed through the new 
javax.persistence.EntityManager service. 

An entity bean implementation is provided in the following 
three files/classes

Beans
Order.java
LineItem.java

Entity Manager
ShoppingCartBean.java

//Order.java
import javax.persistence.CascadeType;
import javax.persistence.Entity;
import javax.persistence.FetchType;
import javax.persistence.GeneratedValue; import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.OneToMany;
import javax.persistence.Table;
import javax.persistence.Id;
import javax.persistence.CascadeType;
import javax.persistence.FetchType;
import java.util.ArrayList;
import java.util.Collection;

@Entity
@Table(name = "PURCHASE_ORDER")
public class Order implements java.io.Serializable
{
   private int id;
   private double total;
   private Collection lineItems;

   @Id @GeneratedValue(strategy=GenerationType.AUTO)
   public int getId()
   {
      return id;
   }

   public void setId(int id)
   {
      this.id = id;
   }

   public double getTotal()
   {
      return total;
   }

   public void setTotal(double total)
   {
      this.total = total;
   }

   public void addPurchase(String product, int quantity, double price)
   {
      if (lineItems == null) lineItems = new ArrayList();
      LineItem item = new LineItem();
      item.setOrder(this);
      item.setProduct(product);
      item.setQuantity(quantity);
      item.setSubtotal(quantity * price);
      lineItems.add(item);
      total += quantity * price;
   }

   @OneToMany(cascade = CascadeType.ALL, fetch = FetchType.EAGER, mappedBy="order")
   public Collection getLineItems()
   {
      return lineItems;
   }

   public void setLineItems(Collection lineItems)
   {
      this.lineItems = lineItems;
   }
}





//LineItem.java
import javax.persistence.Entity;
import javax.persistence.GeneratedValue; import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.ManyToOne;
import javax.persistence.Entity;

@Entity
public class LineItem implements java.io.Serializable
{
   private int id;
   private double subtotal;
   private int quantity;
   private String product;
   private Order order;


   @Id @GeneratedValue(strategy=GenerationType.AUTO)
   public int getId()
   {
      return id;
   }

   public void setId(int id)
   {
      this.id = id;
   }

   public double getSubtotal()
   {
      return subtotal;
   }

   public void setSubtotal(double subtotal)
   {
      this.subtotal = subtotal;
   }

   public int getQuantity()
   {
      return quantity;
   }

   public void setQuantity(int quantity)
   {
      this.quantity = quantity;
   }

   public String getProduct()
   {
      return product;
   }

   public void setProduct(String product)
   {
      this.product = product;
   }

   @ManyToOne
   @JoinColumn(name = "order_id")
   public Order getOrder()
   {
      return order;
   }

   public void setOrder(Order order)
   {
      this.order = order;
   }
}





//ShoppingCartBean.java
Interacts with Order as a plain Java object. The checkout()
 method stores orders with persistence storage by using the 
required EntityManager service.


import javax.ejb.Remote;
import javax.ejb.Remove;
import javax.ejb.Stateful;
import javax.persistence.EntityManager;
import javax.persistence.PersistenceContext;
import javax.persistence.PersistenceContext;


@Stateful
@Remote(ShoppingCart.class)
public class ShoppingCartBean implements ShoppingCart, java.io.Serializable
{
   @PersistenceContext
   private EntityManager manager;
   private Order order;

   public void buy(String product, int quantity, double price)
   {
      if (order == null) order = new Order();
      order.addPurchase(product, quantity, price);
   }

   public Order getOrder()
   {
      return order;
   }

   @Remove
   public void checkout()
   {
      manager.persist(order);
   }
}
 

GNU Distribution Without Warranty License



Comparison EJB 2 and EJB 3



Comparison EJB 2 and EJB 3

 EJB 2.0 has deployment descriptors but EJB 3.0 has no deployment descriptor
 In EJB 2.0 you have to write Home and Remote Interfaces But in EJB3.0 you do not need to write Home interfaces
 In EJB 3.0, all entities are identified with '@' 
 In EJB 3.0 methods like ejbPassivate, ejbActivate, ejbLoad, ejbStore, etc. are not required
 EJB 3.0 is totally newly designed including the entity manager 
 EJB 3.0 entity beans are just POJO 
 No EJB container required to run 
 EJB 3.0 supports Java Persistence API for all of its data needs
 No XMLDeployment Descriptors but annotations
 EJB 3.0 entity beans/JPA becomes local
 Queries are very flexible. Multiple levels of joins are enabled 
 EJB 3.0 pluggable, security enabled 



JDBC: Stored Procedure



Sample stored procedure call using JDBC:
Call stored procedure to change/set a value in the database



//set birthday - supply professor name
try
{
    String professor= "dylan thomas";
    CallableStatement proc = connection.prepareCall("{ call set_birth_date(?, ?) }");
    proc.setString(1, professor);
    proc.setString(2, '1950-01-01');
    cs.execute();
}
catch (SQLException e)
{
    // ....
}

Stored procedures can also return result/data to the caller: like

//return birth day
connection.setAutoCommit(false);
CallableStatement proc =
    connection.prepareCall("{ ? = call birthday_when(?) }");
proc.registerOutParameter(1, Types.Timestamp);
proc.setString(2, professorName);
cs.execute();
Timestamp age = proc.getString(2);

Stored procedures can also return complex data like  resultsets. JDBC drivers from oracle, Sql Server, PostgreSQL support this. 



SCJA: Java Really Basic Stuffs - But you may need to know them for exams like SCJA



SCJA: Syllabus 


http://www.sun.com/training/catalog/courses/CX-310-019.xml


Floating point types: http://java.sun.com/docs/books/jls/second_edition/html/typesValues.doc.html

Enumerated types in Java: http://java.sun.com/docs/books/tutorial/java/javaOO/enum.html

is a finite set of symbolic literals

is represented as first-class object

are allowed in case statements

the literals may be any valid Java identifier



Java Interface

an interface may NOT contain any concrete method implementations

an interface is NOT a class of any style

an interface is NOT a member of a class

An interface defines a set of abstract methods that may have many implementations.




Class Association, Class Composition, dependency:

Compositions may also have navigation methods, but these methods must NOT pass references to the owned objects. This is usually achieved by passing back a copy of the object rather than the owned object itself. 

Composition implies that the owning object controls the life cycle of the owned object

Dependency merely imply that one object uses another object during computations.



disadvantages of proper information hiding?

Access to object attributes incur a runtime penalty.However, the Sun hotspot JVM usually can eliminate the added overhead by "inlining" the methods where they are called.
 
a mutator method is longer than an assignment operation

it is time consuming to use methods to access object attributes rather than direct access.



program to an interface

References to objects should be declared as interfaces rather than concrete classes

the reference variables to objects that need to be as generic as possible. This is the "program to an interface" principle. 



correct representation of an attribute in UML


- attr : int

uml


0..1 indicates zero or one multiplicity, which is how you can represent an optional association. 


? is NOT a valid multiplicity indicator.

* is an abbreviation for 0..*.

M is NOT a valid multiplicity indicator.

? is NOT a valid multiplicity indicator.

 0..* is exactly how to indicate zero or more.



Statement types




Java: Some basic important stuffs


Data types to represent telephone numbers:

a string of ten digits can represent all ten-digit telephone numbers.

an object can hold data (integers or strings) of the elements of a telephone number


an integer data type can represent all ten-digit numbers

--
a boolean can only represent two values

an enumerated type can only represent a fixed number of constant





Abstract Class:



An abstract class may have constructors, but it is illegal to invoke the new operator on an abstract class

An abstract class is allowed to have method implementations

There is no restriction about the placement of abstract classes in a class hierarchy

It is legal for an abstract class to implement an interface and implement one or more interface methods






Design a role player game:

creating an abstract superclass for a generic player will simplify the design. 

This is because the maintenance of the common methods will be simplified.

An abstract class is the perfect container, as a superclass, for the common methods 






Model

A sports team with fixed number of players in which players may participate in other teams

a many-to-many association from players to team Will work



Java Bean convention for setter methods

void setFirstName(String value)





Data Hiding

A well-encapsulated class must have all of its attributes marked private.

A well-encapsulated class must hide all internal methods. This is because this is NOT part of the class's public interface. 

NOT all attributes require accessor or mutator methods.






The principle of "programming to an interface"?



Generalize the return type of a method. The return type of a method should be as abstract as possible, such that any object of that type could be returned. 
If a concrete class is used as the return type, then only an object of that type (or its subclasses) can be returned.



A class hierarchy is a static part of the code structure. Polymorphism and program to an interface are principles that apply to the dynamic aspects of the code, 
such as the objects that are stored in variables and passed through methods.




The parameter type of a method should be as abstract as possible, such that any object of that type could be passed in to the method. If a concrete class is 
used as the parameter type, then only an object of that type (or its subclasses) can be used as a parameter. 

 


The type of an instance variable should be as abstract as possible, such that any object of that type could be held by the owning object. If a concrete class 
is used as an instance variable type, then only an object of that type (or its subclasses) can be held in that variable. 

 

The relationship between classes and interfaces form only a static part of the code structure. Polymorphism and program to an interface are principles that apply to the dynamic aspects of the code




JAVA: Some links: useful for exams like scjp/scja



Assertions in Java: http://java.sun.com/j2se/1.4.2/docs/guide/lang/assert.html 

Enum in Java:http://www.java2s.com/Code/Java/Language-Basics/Enum.htm

StringBuffer and StringBuilder Classes have similar methods where StringBuffer is synchronized: http://java.sun.com/j2se/1.5.0/docs/api/java/lang/StringBuilder.html

Serialize and Deserialize: http://java.sun.com/j2se/1.4.2/docs/api/java/io/Serializable.html

java.util package is very important: http://java.sun.com/j2se/1.4.2/docs/api/java/util/package-summary.html


SCJP: Java Operators



Exams like SCJP test your understanding of Java operators and how to use them like: 

assignment operators: =, +=, -=

arithmetic operators:  +, -, *, /, %, ++, --

relational operators: <, <=, >, >=, ==, !=

logical operators: &, |, ^, !, &&, ||

conditional operators: ? : 

Also operators to check the equality of two objects or two primitives 



In the following table operators and their precedences are shown. Upper rows operators have higher precedence. Same row operators have equal precedence. For equal precedence operators, All binary operators except the assignment operators work from left to right while assignment operators work from right to left. 


 



Operator Precedence


Operators Precedence

	postfix expr++ expr--




	unary ++expr --expr +expr -expr ~ !



	multiplicative * / %


	additive + -


	shift << >> >>>



	relational < > <= >= instanceof


	equality == !=




	bitwise AND &


	bitwise exclusive OR ^


	bitwise inclusive OR |




	logical AND &&


	logical OR ||


	ternary ? :



	assignment = += -= *= /= %= &= ^= |= <<= >>= >>>=




The following quick reference summarizes the operators supported by the Java programming language. 


Simple Assignment Operator

=	Simple assignment operator



Arithmetic Operators
+ 	Additive operator (also used for String concatenation)
- 	Subtraction operator
*	Multiplication operator
/ 	Division operator
%	Remainder operator


Unary Operators
+ 	Unary plus operator; indicates positive value (numbers are positive without this, however)
- 	Unary minus operator; negates an expression
++  	Increment operator; increments a value by 1
--    	Decrement operator; decrements a value by 1
!     	Logical compliment operator; inverts the value of a boolean


Equality and Relational Operators

==	Equal to
!=	Not equal to
>	Greater than
>=	Greater than or equal to
<	Less than
<=	Less than or equal to



	
Conditional Operators
	
&& 	Conditional-AND
|| 	Conditional-OR
?:      Ternary (shorthand for if-then-else statement)


Type Comparison Operator

instanceof	Compares an object to a specified type 






Bitwise and Bit Shift Operators

~	Unary bitwise complement
<<	Signed left shift
>>	Signed right shift
>>>	Unsigned right shift
&	Bitwise AND
^	Bitwise exclusive OR
|	Bitwise inclusive OR








Details about java operators



SCJP: Classpath and Jar



Java certification exams like SCJP test your knowledge about java classpath. Check here for an excellent resource on the topic . 


System classpath


We can specify classpath in the command line or make use of a `system' class path. The IDEs have their own way of maintaining class paths. System class paths will be used by both the Java compiler and the JVM in the absence of specific instructions.

 

Set Linux System Classpath:

CLASSPATH=/myclasses/myclasses.jar;export CLASSPATH 



Windows: 

set CLASSPATH=c:\myclasses\myclasses.jar



For permanent result, in Linux, put the commands in the file .bashrc in your home directory. On Windows 2000/NT,  set it from `Control Panel', System, Environment Variables. 



You can also specify .jar files full of your required classes in your classpath.



CLASSPATH=/usr/j2ee/j2ee.jar:.;export CLASSPATH 



where the `.' indicates `current directory'. 



From command line, if you want to add more paths to the classpath use:



Linux:javac -classpath $CLASSPATH:dir1:dir2 ...



Windows:javac -classpath %CLASSPATH%;dir1:dir2 ...



if you have spaces in your path use double quote to concatenate words.



Also check this resource





SCJP: Topics and Resources : will be continued



SCJP topics and related resources are provided. I have skimed through the resources at least one time.



Garbage Collection


 Test area:Given a code example, recognize the point at which an object becomes eligible for garbage collection, determine what is and is not guaranteed by the garbage collection system, and recognize the behaviors of the Object.finalize() method
 
 Java's Garbage Collected heap
Garbage Collection:Inside the Java Virtual Machine
Garbage collection and performance
Java Garbage Collection Tuning
Garbage Collection - finalize():object.finalize()
USING FINALLY VERSUS FINALIZE TO GUARANTEE QUICK RESOURCE CLEANUP



Parameter Passing

  Test Topic:Determine the effect upon object references and primitive values when they are passed into methods that perform assignments or other modifying operations on the parameters. 


Parameter passing in Java - by reference or by value?:Everything in Java is passed by value. Objects, however, are never passed at all:The values of variables are always primitives or references, never objects.
Pass By Value


Command Line Parameter


  Test Topic: Given an example of a class and a command-line, determine the expected runtime behavior
 Command-Line Arguments
 Command-Line Arguments 


Access Modifiers, Package Declaration, Import


  Test Topic: Given a code example and a scenario, write code that uses the appropriate access modifiers, package declarations, and import statements to interact with (through access or inheritance) the code in the example. 
 Modifiers in Java
 Controlling Access to Members of a Class
 Access Modifiers
Java Access Modifiers
 Java Packages


Concurrency:java.lang.Thread and java.lang.Runnable

 Test Topic: Write code to define, instantiate, and start new threads using both java.lang.Thread and java.lang.Runnable 
 Java Threads
 Exploring Java Threads
 Different ways to create threads



Java Thread:wait/notify/notifyall-lock

  Test Topic: Given a scenario, write code that makes appropriate use of wait, notify, or notifyAll. 
 
 wait(), notify() and notifyAll() in Java - A tutorial 
 
 wait/notify 
 Java Lock Interface
 Threads and Locks
Lock for read and write

 Understanding Java Multithreading and Read-Write Locks

 Java Thread States

Enum Thread.State


OOP Concept 1


  Test Topic: Develop code that implements tight encapsulation, loose coupling, and high cohesion in classes, and describe the benefits
 Tight encapsulation, loose coupling
 Tight encapsulation, loose coupling

 Inheritance and Polymorphism

Overloading and overriding

Overloading and overriding




Finally take a look here for detailed lessons 

Another complete resource





Java Collection Framework




                
                  
                    Array
                  
                  
                    
                      Benefits
                    
                    
                      Constraints
                    

                  
                  
                    
                      
                        Data access is fast.
                        
                        Good for ordered data, which is not
                        changed or searched frequently.
                        
                      
                    

                    
                      
                        Inefficient if number of elements
                        grow.
                        
                        Inefficient if an element to be
                        inserted in middle of collection.
                        
                        Provides no special search mechanism.
                        
                      
                    

                  
                


                

                
                  
                    Linked List
                  
                  

                    
                      Benefits
                    
                    
                      Constraints
                    
                  
                  
                    
                      

                        Allows efficient inserts/delete at
                        any location
                        
                        Allows arbitrary growth of
                        collection.
                        
                        Applying order to the elements is
                        easy.
                        
                      
                    
                    
                      

                        Slower while accessing elements by
                        index.
                        
                        No special search mechanism is
                        provided.
                        
                      
                    
                  
                


                

                


                
                  
                    Tree
                  
                  
                    
                      Benefits
                    
                    
                      Constraints
                    

                  
                  
                    
                      
                        Easy addition/deletion in middle.
                        
                        Allows arbitrary growth.
                        
                        A better and efficient search
                        mechanism.
                        

                      
                    
                    
                      
                        Ordering is peculiar and some
                        comparison mechanism is required.
                        
                        Searching is not efficient for
                        unevenly distributed data.
                        
                      
                    

                  
                


                

                

                
                  
                    Hashtable
                  
                  

                    
                      Benefits
                    
                    
                      Constraints
                    
                  
                  
                    
                      

                        Efficient searching.
                        
                        Good access mechanism.
                        
                        Allows arbitrary growth of
                        collection.
                        
                      
                    
                    
                      

                        Not good for small data set because
                        of overheads.
                        
                        Overhead for storing keys for the
                        values in collection.
                        
                        Overhead of hashing scheme.
                        
                      
                    
                  
                



              
       






SCJP: Language Fundamentals



Class declaration and java source file.

  Only "one" top-level public class is allowed per java source file.
 
 The name of the java source file and the name of the top-level public class MUST be the same.
 
 If no public class is there in a file, after compiling separate class files will be created for all classes in the file. 
 
 Package statement, import statements and class definition MUST appear in the order given.

Keywords and Identifiers

   Keywords are always in a lower case.
  
 Some keywords: const, goto, strictfp, and volatile
   
 Identifiers must start with either letter, $ or _ (underscore) and can have letter, $, _ or digits in it.
  
	no keyword is allowed as identifiers

  
      
        
          abstract
        
        
          do
        
        

          import
        
        
          public
        
        
          transient
        
      
      

        
          boolean
        
        
          double
        
        
          instanceof
        
        

          return
        
        
          try
        
      
      
        
          break
        

        
          else
        
        
          int
        
        
          short
        
        

          void
        
      
      
        
          byte
        
        
          extends
        

        
          interface
        
        
          static
        
        
          volatile
        
      

      
        
          case
        
        
          final
        
        
          long
        

        
          super
        
        
          while
        
      
      
        
          catch
        

        
          finally
        
        
          native
        
        
          switch
        
        

        
      
      
        
          char
        
        
          float
        
        

          new
        
        
          synchronized
        
        
        
      
      
        

          class
        
        
          for
        
        
          package
        
        
          this
        

        
        
      
      
        
          continue
        
        
          if
        

        
          private
        
        
          throw
        
        
        
      
      

        
          default
        
        
          implements
        
        
          protected
        
        

          throws
        
        
        
      
    

Default Values, Local Variables

   Each primitive data type has a default value
       specified. Variable of primitive data type may be
       initialized
       
 Only class member variables are automatically
           initialized. Method variables need explicit
           initialization
       
 Local variables (also known as automatic
           variables) are declared in methods and in code
           blocks 
       
 Automatic variables are not automatically initialized 
	
 local variables should be explicitly initialized before first use. These are automatically destroyed when they  go out of scope


Arrays

 Fixed-sized ordered collection of homogeneous data elements 


 int[] ints;          // array declaration 

 ints = new ints[25]; // array construction at runtime. 



Array declared, constructed and initialized at the same time.

 int[] ints = {1,2,3,4,5}; // array declaration, 
 An array of primitive data type created using the new keyword is automatically initialized. Each array element is initialized to its default value. 

For example,

 char[] arrayOfChars = new char[10];


Array of object references: An array of object references created using the new keyword is also initialized. Each array element is initialized to its default value, i.e. null.

String[] names = new String[10];
 length is a property of array (and not a method)
 java.lang.Object is the superclass of an array


Argument passing during method calls

  Always a copy of argument value is passed to calling  method
  
 Arguments of primitive data types: first, a copy of the passing variable is made and then it is passed. The original copy remains unaffected 
 
 Object reference as an argument: A copy of object reference is passed for method calls. It still points to the same object. The original copy is affected. 




SCJP: Garbage Collection



Garbage Collection


   Java itself does memory management. You do not need to allocate memory at the time of object creation; also you do not need to free memory explicitly
 
 Object is created either on the heap or on a stack
 
 Memory heap: Objects created with new keyword are placed in heaps. This memory remains allocated throughout the life cycle of the object. When the object is no more referred, the memory becomes eligible for garbage collection 
 
 Stack:  During method calls, objects are created for method arguments and method variables. These objects are created on stack. Such objects are eligible for garbage-collection when they go out of scope.
 
 Garbage Collection is a low-priority thread in java
 
 Garbage Collection cannot be forced explicitly. JVM may do garbage collection if it is running short of memory.
 
 The call System.gc() does NOT force the garbage collection but only suggests that the JVM may make an effort to do garbage collection.
  
 Garbage Collection is hardwired in Java runtime system. Java runtime system keeps the track of memory allocated. Therefore, it is able to determine if memory is still usable by any live thread. If not, then garbage collection thread will eventually release the memory back to the heap.
    
 Garbage Collection usually adopts an algorithm, which gives a fair balance between responsiveness (how quickly garbage-collection thread yields?) and speed of memory recovery (important for memory-intensive operations). Responsiveness is especially important in real time systems.
    
 An object is eligible for garbage collection when no object refers to it.
    
 An object also becomes eligible when its reference is set to null. (Actually all references to the object should be null for it to be eligible.)
    
 The objects referred by method variables or local variables are eligible for garbage collection when the method or their container block exits



SCJP: Flow controls and exception



Flow Control and Exceptions
Flow control statements

    Conditional:  if, if-else and switch-case
   
 Looping: for, while, do-while
   
  Exception handling: try-catch-finally, throw
   
  Ad hoc flow control: break, continue with or without labels


switch statement
     
    switch(expression){ 

        case ConstantExpression: statement(s); 

        case ConstantExpression: statement(s);

        .

        .

        .

        default: statement(s);


      }





     expression: must be char, byte, short, or int, or a compile-time error occurs
    
 long primitive can be used if type casted to int 
    
 Object reference cannot be used as expression 
    
 Every case expression must be unique
    
 break statement may be used at the end of a case statement, to discontinue execution. 
    
 There can be at most only one default statement.  
    
 The order of case statements and default can be anything.

break and continue

    A break statement transfers the control out of an enclosing statement. break used within a loop breaks the execution of the current loop. In case of nested loops, the break statement passes the control to the immediate outer loop.
    
 A continue statement breaks the current iteration and moves to next iteration.
    
 break and continue with labels.
     
           Labels specify the target (statement) for continue and break
          
 continue with label does not jump to the labeled statement but instead jumps to the end of the labeled loop.
          
  Same label identifiers can be reused multiple times as long as they are not nested.
          
  Label names do not conflict with the same named identifier(variable, method or class name).
       



Checked and Unchecked Exceptions
    Checked Exceptions

           Checked Exceptions are checked by the compiler to see if these exceptions are properly caught or specified. If not, the code will fail to compile
          
 Checked exception forces client program to deal with the scenario in which an exception may be thrown
          
 Checked exceptions must be either declared or caught at compile time


    Unchecked Exceptions

           Unchecked exceptions are RuntimeException and all of its subclasses.
          
 Class java.lang.Error and its subclasses also are unchecked.
          
 Unchecked Exceptions are not checked by the compiler. 
          
 Runtime exceptions do not need to be caught or declared.





Code Conventions for the Java Programming Language



Why Have Code Conventions?

     80% of software life cycle is spent on software
         maintenance.
    
 Hardly the original author maintains a software
    
 Code Conventions improve the readability of the 
         software
    
 If you require to ship your source code as a product,
         code conventions make your product well packaged 

Java Code Conventions

     Avoid assigning several variables to the same value 
         in a single statement
    
 Avoid using an object to access a class (static) 
         variable or method. Use a class name instead
    
 Don't make any instance or class variable public 
         without good reason. When the class is essentially 
         a data structure, you can use public instance 
         variables
    
 Two blank lines: Between sections of a source file,
          between class and interface definitions 
    
 One blank line: Between methods, between the local 
         variables in a method and its first statement, 
         before a block or single-line, between logical 
         sections inside a method 
   
 Blank spaces: Between a keyword and parenthesis, 
        after commas in argument lists, after Casts 
   
 Each line should contain at most one statement 
   
 One declaration per line is recommended 
   
 Initialize local variables where they're declared
   
 Put declarations only at the beginning of blocks 
   
 No space between a method name and the parenthesis
   
 Methods are separated by a blank line
   
 Four styles of implementation comments: block, 
        single-line, trailing, and end-of-line
   
 Documentation comments describe Java classes, 
        interfaces, constructors, methods, and fields. Use 
        /**...*/ for doc comments
   
 Doc comments: One comment per class, interface, or 
        member 
   
 Doc comments: Should appear just before the 
        declaration
   
 Avoid lines longer than 80 characters
   
 Break longer lines: after a comma, before an
        operator, Prefer higher-level breaks to lower-level 
        breaks, align new lines with the previous line, or 
        indent the new line with  8 spaces 
    
 You can get a detailed code conventions at Java Code Conventions





SCJP: Class Declarations



class declarations 

    Start with modifiers such as public, private followed 
        by class keyword
   
 The class name, with the initial letter capitalized 
   
 The name of the class's parent (superclass), 
         preceded by the keyword extends (if any). A class can
         only extend (subclass) one parent.
    
 list of interfaces implemented by the class,  
         preceded by the keyword implements (if any). A class 
         can implement more than one interface
     
 The class body, surrounded by braces, {}.
     
 Class member variable declarations
     
              Requires three components, in order:
             
 Zero or more modifiers, such as public or 
                  private
             
 The field's type
             
 The field's name.
     


Abstract Classes

  A class declared with abstract keyword is an abstract 
      class. It may or may not include abstract methods
 
 Abstract classes cannot be instantiated
 
 Abstract classes can be subclassed
 
 Class containing abstract methods, must be declared to
      be abstract 
 
 Abstract methods are methods declared without 
      implementation (braces)
 
 The subclass of an abstract class must provide 
      implementations of all the abstract methods otherwise 
      the subclass itself needs to be declared as abstract.
 
 An abstract class may have static and final fields and 
      methods. Interfaces can not
 
 If an abstract class contains only abstract method 
      declarations with no implementations, it should better
      be declared as an interface 
 
 It's a good design to declare a common abstract class with common methods with implementations for several very related classes (will extend the abstract class)
 
 An abstract class can implement an interface but are 
     not bound to implement all interface methods  


Nested Classes

  Classes declared under another class are called nested 
      classes
 
 Two types: Static Nested: declared with static keyword, Inner Nested: declared with no static keyword
 
 inner classes have access to other members of the 
      outer class including private members
 
 Static nested classes do not have access to other 
      members of the outer class 
 
 Static nested classes are accessed using the outer 
      class name such as: OuterClass.StaticNestedClass
 
 To use inner classes, the outer class must be instantiated first. Then, inner object can be created as follows: 
OuterClass.InnerClass innerObject = outerObject.new InnerClass();
 
 Local inner classes: Declared within the body of a 
      method
 
 Anonymous inner classes: Declared within the body of 
      a method without naming it
 
 Inner classes may have similar access modifiers like 
      other outer class members
 
 Why use nested classes:
      
            For logically grouping classes that are only
                used in one place
           
 It increases encapsulation.
           
 May lead to more readable and maintainable 
                code

         









SCJP: Interfaces



Interface

    An interface is a reference type, similar to a class  
   
 Interfaces can contain only constants, method 
         signatures, and nested types 
    
 No method is implemented 
    
 Interfaces cannot be instantiated
    
 They can only be implemented by classes or extended 
         by other interfaces
     
 Interfaces are not part of the class hierarchy
     
 A class can implement multiple interfaces



SCJP: Random Stuffs




    An enum may NOT be declared in a method
   
 An enum can be imported
   
 If the JVM has a choice, it will select a method 
        without varargs before selecting a method with 
        varargs
   
 When enums are equal, both .equals and == always 
        return true
   
 The headMap() method returns the portion of the map 
        whose keys are less than the key sent to it
   
 The asList() method of Arrays creates a fixed-size 
        list that is backed by the array, so no additions are 
        possible.
   
 A static initialization block is a normal block of 
        code enclosed in braces, { }, and preceded by the 
        static keyword. Used to initialize class variables
   
 All enums implicitly extend java.lang.Enum.
   
 A class can extend only one other class, an 
        interface can extend any number of interfaces
   
 An interface might also contain constant 
        definitions.
  
 An abstract class that implements an interface may 
       not implement all interface methods



Java : SCJP: Important Resources




  How to use generics to avoid runtime errors.
 More Generics
 
 Class casting in Java: How to avoid runtime exception - ClassCastException: overloading, overriding, variable and method hiding
 
 Java HotSpot virtual machine
  
 What Java Technology can do?
  
 Offers from Java Technology
  
 Java:Common Problems (and Their Solutions)
 
 Benefits of OOP: Modularity, Information-hiding, Code re-use, Pluggability and debugging ease
 Object oriented concepts in Java
 Variable Naming Conventions in Java
 Java Primitive Data Types
 Java : Arrays: System.arraycopy method
 Java Operators: Carefully look about precedence
 continue and break statements in Java
 Annotations in Java
 Passing Parameters, System.out.printf, Shadowing Variables
 The Garbage Collector
 You can use interface names as return types. The object returned must implement the specified interface.
 when a class name is used as a return type, the returned object must be either a subclass of, or the exact class of, the return type
 Controlling Access to Members of a Class
 Java initializing variables: initialize at declarations, Static Initialization Blocks, private static method to initialize, Initializer blocks for instance variables, A final method for initialization
 Nested Classes
 enum in Java:  enums implicitly extend java.lang.Enum. An enum cannot extend anything else. Enums can have methods like classes
if a variable is declared to be the type of an interface, its value can reference any object that is instantiated from any class that implements the interface
 Interfaces provide an alternative to multiple inheritance
 Java Interfaces
 Rewriting Interfaces
 Covariant return type: An overriding method can return a subtype of the type returned by the overridden method
 The access modifier for an overriding method can allow more, but not less, access than the overridden method
 Hiding fields makes code difficult to read
 java.lang.Object as a super class
 final methods can not be overridden, final classes can not be sub-classed, methods called from constructors should generally be declared final (otherwise, a different implementation of the method in subclasses may create unwanted results)
Interfaces can not have static or final methods
 System.out.format(.....) and String.format() can be used as alternatives to System.out.println()
 Using Number class vs. primitive data types
 String, StringBuilder, StringBuffer: StringBuilder has capacity(), reverse() methods that String does not have. StringBuffer = StringBuilder but StringBuffer  is thread-safe i.e. synchronized. String, and StringBuilder can be converted to each other
 Three kinds of exceptions
  Chained Exceptions: Stack Trace: Logging



SCJP: Basic Java I/O



  

      ByteStream is the basic I/O stream. Handles data as 
          a stream of bytes. Does operation with byte unit and
          uses 8 bit. FileInputStream, FileOutputStream - can 
          be used to copy files as byte by byte.
     
 Character Streams: FileReader and FileWriter are 
          character streams. They treat file data as 16 bit 
          unicode charater streams.
     
 InputStreamReader, OutputStreamWriter are also 
          character streams. May be used in socket data 
          reading.
     
 Line-Oriented I/O: BufferedReader and PrintWriter
     
 Buffered Streams: BufferedInputStream and 
          BufferedOutputStream create buffered byte streams, 
          while BufferedReader and BufferedWriter create 
          buffered character streams
     
 You can set autoflush()  of buffered streams or 
          call manually flush() method.
    
 The scanner API breaks input into individual 
         tokens. The formatting API assembles data into 
         nicely formatted, human-readable form.
    
 Scanner: 

Scanner scanner = new Scanner(new BufferedReader(new FileReader("test.txt")));



            while (s.hasNext()) {
                System.out.println(s.next());
            }



    
 To create formatted output streams, instantiate 
         PrintWriter not PrintStream
    
 Check: System.out.format("The square root of %d is %f.%n", i, r);
     
 System.out and System.err are  
          PrintStream objects. PrintStream is really a byte
           stream but uses some mechanism to emulate 
          character stream.
     
 InputStreamReader cin = new 
InputStreamReader(System.in); System.in is a byte stream. InputStreamReader is used to emulate a character stream.
    
 System.console provides character streams to handle
         console read/write operations. Provides readPassword  method to read password from the console
     
Data Streams: Support I/O operations of primitive 
         data types. DataInputStream and DataOutputStream.
     
 Check: 

out = new DataOutputStream(new
            BufferedOutputStream(new FileOutputStream(dataFile)));
out.writeDouble(prices);
out.writeInt(units);
out.writeUTF(descs);
    
 DataStreams detects an end-of-file condition by catching EOFException
Correct type to represent currency values: java.math.BigDecimal - an object type

Object Streams: ObjectInputStream and ObjectOutputStream. Use writeObject and readObject to write and read objects respectively.
 A stream can contain only one copy of an object but many references to it when required.
 File Objects: File I/O
 Random access file: 

new RandomAccessFile("test.txt", "r");
new RandomAccessFile("test.txt", "rw");

RandomAccessFile methods:

    * int skipBytes(int) 
    * void seek(long)  
    * long getFilePointer() 
 

 The new java.nio.*  package provides supports to handle 
     file i/o for high performance applications.
     


SCJP: Java Concurrency




   Java High Level Concurrency Objects
  
 constructors cannot be synchronized
  
 Liveness of multi-threaded applications
 Immutable Objects
 An application may have one or more processes. A process may have one or more threads.
Two ways to create threads
Thread.sleep(4000); To pause a thread. The time like 4000 ms is really dependent on the os and not precise
 Thread Interrupts
Thread Join
Regular Expression
 Regular expression - meta characters: ([{\^-$|]})?*+.
 Character Classes for Regular Expressions
 Pattern Class
 Matcher Class
 System.getenv(): get environment variables in a hashmap.
 System.getProperty("path.separator"); System.setProperties : read and write system properties.
How to use Properties to keep application properties
 Access SecurityManager: SecurityManager appsm = System.getSecurityManager();



Java: Collections Frameworks



 

     Core collection interfaces: Collection (Set(SortedSet), List, Queue), Map(SortedMap)
    
 A Map is not a true Collection.
    

 public interface Collection extends Iterable {
    // Basic operations
    int size();
    boolean isEmpty();
    boolean contains(Object element);
    boolean add(E element);         //optional
    boolean remove(Object element); //optional
    Iterator iterator();

    // Bulk operations
    boolean containsAll(Collection c);
    boolean addAll(Collection c); //optional
    boolean removeAll(Collection c);        //optional
    boolean retainAll(Collection c);        //optional
    void clear();                              //optional

    // Array operations
    Object[] toArray();
     T[] toArray(T[] a);
}

 Traverse collections:
for (Object o : collection)
    System.out.println(o);

 You can also use Iterator to traverse through collections. like:     for (Iterator it = c.iterator(); it.hasNext(); )

 Use iterator over for construct to remove an item from the collection or to iterate parallelly two or more collections.

 Collection to array: String[] a = c.toArray(new String[0]);

 Each Queue method exists in two forms: (1) one throws an exception if the operation fails, and (2) the other returns a special value if the operation fails
Collections represent data items that form a natural group
 All general-purpose collection implementations have a constructor that takes a Collection argument. This constructor (conversion constructor), initializes the new collection to contain all of the elements in the specified collection 
 List list = new ArrayList(c) - where c is a Collection
 Remove all of the null elements from a Collection c:
    c.removeAll(Collections.singleton(null));
 Set can not contain duplicate elements. Hence, converting any collection to a set can remove duplicate elements from the collection. Example: Collection noDups = new HashSet(c);
The Set interface contains only methods inherited from Collection 
 Set overrides equals method of the Object class. Two Set instances are equal if they contain the same elements.
 Set implementations: HashSet, TreeSet, and LinkedHashSet. HashSet: uses hash table to store data, the best-performing implementation, not ordered. TreeSet: uses red-black tree as storage, ordered, substantially slower than HashSet. LinkedHashSet: uses hash table as storage with a linked list running through it, ordered according to the insertion order
 HashSet fastest, LinkedHashSet average, TreeSet slowest among sets
 s1.addAll(s2) - s1 union s2 : s1, s2 are sets
 s1.retainAll(s2) - s1 intersection s2
 s1.removeAll(s2) - s1 subtract s2

 Java List Interface
public interface List extends Collection {
    // Positional access
    E get(int index);
    E set(int index, E element);    //optional
    boolean add(E element);         //optional
    void add(int index, E element); //optional
    E remove(int index);            //optional
    boolean addAll(int index,
        Collection c); //optional

    // Search
    int indexOf(Object o);
    int lastIndexOf(Object o);

    // Iteration
    ListIterator listIterator();
    ListIterator listIterator(int index);

    // Range-view
    List subList(int from, int to);
}

List: types of operations: Positional access, Search, Iteration , Range-view  
 List types: ArrayList, LinkedList, Vector (retrofitted to implement List) 
 Concatenate two lists: List list3 = new ArrayList(list1);
list3.addAll(list2);
 List has its own Iterator called ListIterator that can move in both directions
 List algorithms: # sort , 
 shuffle ,reverse ,rotate , swap ,replaceAll ,fill , copy ,binarySearch ,indexOfSubList ,lastIndexOfSubList 
 To generate sublist use subList(fromIndex,toIndex)
 Queue methods add, remove, and element throw exception (illegalStateException, NoSuchElementException) in case of errors while offer, poll, peek return null or false in case of errors.
 Null is not a recommended value for queue as they return null in case of errors. Queue doesn't support null values where LinkedList version of Queue supports.
 Like Set Maps are of three kinds HashMap, TreeMap, LinkedHashMap and HashTable is retrofitted to Map.
 Performance order: HashMap, HashMap, TreeMap, LinkedHashMap, TreeMap
 Sorting collections: If you try to sort a list, the elements should implement Comparable otherwise  Collections.sort(list) will throw a ClassCastException. 
 You can also create Comparator object for sorting and use Collections.sort(list, comparator). but the list elements should be comparable to one another using the comparator
 SortedSet is a set whose values are sorted according to the natural order or the provided comparator object at creation.
 it's okay to use range-views on sorted sets for long periods of time, unlike range-views on lists.
Two range-view methods of SortedSet:
 SortedSet volume1 = dictionary.headSet("n"); From first but does not include "n", until "n" 

SortedSet volume2 = dictionary.tailSet("n");: from "n" to the end of the set.
 SortedMap has similar methods like SortedSet

 From this point implementations of the interfaces (collection related) will be discussed
 HashSet, ArrayList, and HashMap are the most used collections
 TreeSet and TreeMap implementations came from SortedSet and SortedMap interfaces respectively
 Queue implementations: LinkedList: FIFO, PriorityQueue: Ordered according to values
 General-purpose implementations: None are synchronized (thread-safe). All have fail-fast iterators, are Serializable, and  support a public clone method.
 Thread-safe collections: the synchronization wrappers, allow any collection to be transformed into a synchronized collection
 The java.util.concurrent package: Implements BlockingQueue interface, which extends Queue, and ConcurrentMap interface, which extends Map. Much higher concurrency than mere synchronized implementations
 


SCJP: Rules



 

      A class's superclasses don't have to implement 
          Serializable in order to be serialized
     
 if a superclass doesn't implement Serializable then 
          it's constructor will run during deserialization 
     
 A transient variable's state is lost during 
          serialization, but a volatile variable's state is 
          not lost
     
 Java:Volatile variable
     
 Transient  Variable
     
 NumberFormat, Calendar,  DateFormat are abstract 
          classes. Use the getInstance method to get  
          NumberFormat instances.
     
 The + quantifier in a regular expression indicates
           1 or more occurrences, * indicates 0 or more, [] 
           just one character in the group, () indicates a 
           whole group match.
     
 The default separator in Scanner class is a blank 
         NOT a comma
     
 Multiple threads can be created using the same 
          Runnable object, but a given thread can be started
          only once.
     
 Thread.yield(): Causes the currently executing 
          thread object to temporarily pause and allow other
          threads to execute.
     
 Thread.join():  Waits for this thread to die.
     
 Wait(), Notify(), NotifyAll() methods
     
 Low coupling: classes know the least possible 
          about each other, is preferable over tight 
          coupling. 
      
 High cohesion: Each class has well focused 
           responsibilities. Is preferable over low 
           cohesion.
      
 Polymorphism does NOT apply to static methods.
      
 Instance variable cannot be referenced from 
            static method 
 


Sun certifications: Topics



 

      Enterprise Architect 
     
 Business Component Developer  
     
 Web Component Developer 
     
 Sun Certified Developer for Java Web Services 
     
 Mobile Application Developer 
 


SCEA:Security in Java: Potential threats to a system and how to address the threats:Java Enterprise Architect




   Input Validation Failures: Input should be validated 
       both at the client end and the server end (before any 
       processing). Validating both from trusted and untrusted
       sources is important. Otherwise code injection attack 
       may happen. Validation should include: data type 
      (string, integer), format, length, range, null-value 
       handling, verifying for character-set, locale, 
      patterns, context, legal values and validity, and so on.
   
Output Sanitation: If you display the user entered values or if the generated output contains a significant use of the input values, in some cases, the user may be able to relate the output to the input. The user may provide malicious data to display say a pop up or an affiliate ad or to break the system. 
   
Buffer Overflow: Some users may try to cause 
         buffer overflow and hence, break the system. This 
         may be part of a denial of service attack. Suppose 
         you have set a not null table column to be of size 
         50 and did not validate the input, then data > 50 
         chars may break the system based on the operations
         and platforms. Or a user can just insert huge 
          amount of data to eat up your server resources.
   
Data Injection Flaw: In this case, security intruders can try to pass sql queries as part of their data to get useful information or to break your system. 
   
Cross-Site Scripting (XSS):
   
Improper Error Handling: In case of errors, 
       such as, out of memory, null pointer exceptions, 
       system call failure, database access failure, network
       timeout many applications display detailed internal 
       error messages. Based on the error messages (weak 
        points), hackers may be able to design an attack.  
   
Insecure Data Transit or Storage: Data in 
          storage or transit when represented as plain text 
          are vulnerable to attack. Encryption algorithms 
          may help in these situations.
   
Weak Session Identifiers: If you assign 
          session identifiers before user authentication or 
          display session identifier in plain text, hackers 
          may spoof user identity and do harmful business 
          transactions.
   
Weak Security Tokens:
   
Weak Password Exploits: Passwords, many times,
          can be guessed or watched or retrieved by using 
          password-cracking tools to obtain data from 
          password files. Strong authentication or 
         multifactor authentication mechanisms using digital
         certificates, biometrics, or smart cards is 
          strongly recommended. 
   
Weak Encryption:
   
Session Theft:
   
Insecure Configuration Data:
   
Broken Authentication:
   
Broken Access Control:
   
Policy Failures:
   
Audit and Logging Failures:
   
Denial of Service (DoS) and Distributed DOS (DDoS):
   
Man-in-the-Middle (MITM):
   
Multiple Sign-On Issues:
   
Deployment Problems:
   
Coding Problems:



SCJP: Short Notes



   

        For the package 
      package com.sun2;
public enum Seasons {SUMMER, FALL, WINTER, SPRING}
      
Valid import statements are:
import com.sun2.Seasons; // the class 
import static com.sun2.Seasons.*; //all enum values
import static com.sun2.Seasons.FALL; //only one enum value

 An interface can extend many interfaces
Interfaces can have variables, overrides and overloads
 An enum can have methods and can override those methods for a specific enum constant
 var-args can be used to pass arrays, var args can be of 0 or more lengths
 A var-args argument must be a method's last argument
 An override cannot change the return type. Override can use covariant as a return type
 Overloading does not depend on the return type
 From J2se 5.0, a method in a subclass may return an object whose type is a subclass of the type returned by the method with the same signature in the superclass
  When a subclass constructor does not explicitly invoke a superclass constructor, the no-argument constructor of the superclass is automatically called from the subclass constructor. If the super class does not have a no-argument constructor, a compile-time error is displayed
 When subclasses override superclass methods, these superclass methods can be accesses using the super keyword (from subclass methods)
 From java 1.5, enums can be used in a switch
 To enable asserts in java program use -ea switch.
 assert has two forms: assert Expression1 ;,  assert Expression1 : Expression2 ;. In the first form only AssertionErorr is displayed, in the second form you can add additional message(Expression2) to the AssertionError. Assert when finds its arguments to be false, it throws AssertionError
 Good places to use assertions: Internal Invariants,     Control-Flow Invariants,  Preconditions, Postconditions, and Class Invariants 
bad use of assertions: argument checking in public methods, to do any work that your application requires for correct operation
 Assertions should be free of side effects: evaluating the expression should not affect any state that is visible after the evaluation is complete
 An overriding method does not need to throw the overridden method's exception
 Nesting try/catches are ok and normal flow rules apply in case of nesting.
 Accessing uninitialized instance/class wrapper variables (Integer, Short) will cause NullPointerException
 NumberFormatException extends IllegalArgumentException
 JVM when calling a method, to make data types compatible, will widen the parameters before boxing. 
 java.io.Console class: Only a single instance exists for a given JVM, All of the methods that read user input are synchronized
 Among File, FileReader, BufferedReader only BufferedReader has a readLine method
 A class's superclasses don't have to implement Serializable in order to be serialized
 if a superclass doesn't implement Serializable then it's constructor will run during deserialization. 
 A transient variable's state is lost during serialization
 A volatile variable's state is not lost during serialization
 If Dog has-a Collar, then Collar must implement java.io.Serializable in order to serialize an instance of Dog.
 If Dog extends Animal and Animal implements java.io.Serializable but Dog does NOT implement java.io.Serializable, you can serialize an instance of Dog.
 Serialization rules: # Rule #1: The object to be persisted must implement the Serializable interface or inherit that implementation from its object hierarchy,
# Rule #2: The object to be persisted must mark all nonserializable fields transient
 To make thread instance unserializable: transient private Thread animator;
 java.lang.Object does not implement Serializable. AWT and Swing GUI components, strings, and arrays -- are serializable
 Serialization Details
 NumberFormat, Calendar, and DateFormat are abstract. Use the getInstance method to get instances.
 For java.util.Scanner, the default separator is a blank NOT a comma
 Multiple threads can be created using the same Runnable object, but a given thread can be started only once
Two invocations of synchronized methods on the same object to interleave - is not possible. When one thread is executing a synchronized method for an object, all other threads that invoke synchronized methods for the same object block (suspend execution) until the first thread is done with the object. When a synchronized method exits, it automatically establishes a happens-before relationship with any subsequent invocation of a synchronized method for the same object. This guarantees that changes to the state of the object are visible to all threads. 
 In object oriented design, low coupling is more desirable than high coupling. High cohesion is more desirable than low cohesion. Coupling: class interdependence. Cohesion: Class activities should be well focused.
 Polymorphism does NOT apply to static methods
 Polymorphic calls and co-variant returns can be mixed 
 no modifier (package private) is weaker than protected. The order is: public, protected, package private, private
 Kind of' translates to extends, 'contract' translates to implements, and 'composed' translates to a has-a implementation.
 TreeMap: headMap() method returns keys that are less than the argument, and tailMap() returns keys that are greater than(>=) the argument.

   


Java Design Patterns: Architectural Frameworks



   

       Sun helps eBay create technology architecture for the future.
      
 J2EE DESIGN PATTERNS Tutorial

      
 Core J2EE Patterns: Patterns index page
      
 J2EE Patterns Catalog
      
 Patterns Tutorial

 Java Design Pattern Books: Preview

   


Java: Common Architectures




Common Architectures
Two tier architectures
Three tier architectures
Multi-tier architectures
Rich clients and browser-based clients in respect of Java EE applications
Web Services



SCJP: More Rules



  

      java -classpath gFolder/Game.jar civilization.java: 
          In such command, -classpath will override (replace) 
          CLASSPATH environment variable.
    
 java -classpath gFolder/Game.jar civilization.java: 
         if both gFolder and current directory contain 
         Game.jar then the jar file under gFolder will be 
         used.
    
 If you want java compiler to recognize your jar file,
         either you have to mention the location of the jar 
         file in javac command using -classpath switch or you 
         have to add the jar file in the CLASSPATH environment
         variable. Mentionable - you need to add the file, 
         adding upto the directory will not work.
   
 Garbage collection: can Java program run out of 
        memory? yes.
   
 Can objects be garbage collected even if it has a 
        valid reference? yes. when no live thread 
        has access to the object.
   
 Can Objects created within inner classes be eligible 
        for garbage collection.? yes. 
   
 Do garbage collector deletes objects from the stack?
        No. As objects reside in heaps not in the stack. 
   
 If an object's finalize method runs to completion 
        will it always be garbage collected? No. The 
        finalize method may create some other references.
   
 Arrays.equals(Object[] a1, Object[] a2) : Returns true if 
        the two specified arrays of Objects are equal to one
        another
    
 The results of Binary search on an unsorted array 
         are undefined
    
 <A extends Alpha> Alpha go(int i) is a valid method
         declaration with a generic return type. class 
         Alpha{}
  


SCJP Practice Exams



Check these practice exams. Be careful that many java rules may have changed over the time. Check that which jdk version or the exam these practice exams support

   http://www.jchq.net/mockexams/exam2.htm
 20 practice exams
 Java Ranch
 JavaRanch
 Self Tester
  Marcus Green's Mock Exam 1
 Marcus Green's Mock Exam 2
  Marcus Green's Mock Exam 3
  Sun's SCJP2 Site

 John Hunt's Mock Exam

  John Meyer's exam

 eXamulator

 Poddar's Questions

 MindQ Mock Exam 

 Sreenivasa Kumar Majji's Questions 

 Barry Boone's Mock Exam 

 JDCert

 Exam 

 IBM's Certification Exam Tool

 Exam Simulator

 Valiveru's Mock Exam 

 Mock Exam Engine

 Practice Questions

 Certification Exam Preparation

 4 Mock Exams

 Java Quizzes

 JavaPrepare.com Test

 JavaCaps.com 

 4Tests.com 

 TipSmart.com

 TestCafe MockTest

 Valentin's Mock Exam 

 Dan Chisholm's Mock Exam

 JavaCoding.net's Mock Exam 

 VooDoo Exam


 JavaBlackBelt

 JavaBlackBelt Intermediate 

 JavaBlackBelt Mock Exams 

 eJavaGuru

 cafe4java 

 cafe4java 

 JavaBeat

 etattva








SCJP Essential Knowledge




   int x=5; String y="3"; System.out.print(x + 1 + y); 
       Output: 63
  
 When there is no live reference to an object, the 
       object becomes eligible for garbage collection. 
  
 The concrete interface method implementation must be 
       public.
  
 When a class implements Comparator, it must implement 
       a compare method.
  
 When a class implements Comparable, it must implement 
       a compareTo method.
  
 The Arrays.asList() method creates a fixed-size list 
  
 A method like void go(Set a) can be called 
       with objects created as: TreeSet t = new TreeSet(); 
       TreeSet t = new TreeSet();. Remember,
       TreeSet t = new TreeSet();
      TreeSet t = new TreeSet(); will not work 
       where Dog is a sub-class of Animal.
  
 When two enums are equal, both .equals and == always 
       return true.
  
 TreeSet is ordered in their natural order or 
       according to the Comparator provided at creation.
  
 SortedMaps are abstract
  
 Is-a relationships can use inheritance
  
 Tightly encapsulated classes can have a has-a 
       relationship
  
 is-a or has-a relationships does not apply to methods
  
 java command in details: Usage: java [-options] class [args...]
           (to execute a class)
   or  java [-options] -jar jarfile [args...]
           (to execute a jar file)

where options include:
    -client	  to select the "client" VM
    -server	  to select the "server" VM
    -hotspot	  is a synonym for the "client" VM  [deprecated]
                  The default VM is client.
                  
    -cp 
    -classpath 
                  A ; separated list of directories, JAR archives,
                  and ZIP archives to search for class files.
    -D=
                  set a system property
    -verbose[:class|gc|jni]
                  enable verbose output
    -version      print product version and exit
    -version:
                  require the specified version to run
    -showversion  print product version and continue
    -jre-restrict-search | -jre-no-restrict-search
                  include/exclude user private JREs in the version search
    -? -help      print this help message
    -X            print help on non-standard options
    -ea[:...|:]
    -enableassertions[:...|:]
                  enable assertions
    -da[:...|:]
    -disableassertions[:...|:]
                  disable assertions
    -esa | -enablesystemassertions
                  enable system assertions
    -dsa | -disablesystemassertions
                  disable system assertions
    -agentlib:[=]
                  load native agent library , e.g. -agentlib:hprof
                    see also, -agentlib:jdwp=help and -agentlib:hprof=help
    -agentpath:[=]
                  load native agent library by full pathname
    -javaagent:[=]
                  load Java programming language agent, see java.lang.instrument




SCWCD: Essential Knowledge : Web Development in Java



  

    HttpServlet request servicing methods: Java Servlet Specification, Version 2.4 (pgs 23, 231)
    
         doGet() to process HTTP GET requests
        
 doPost() method to process HTTP POST requests
        
 doGet() method will process HEAD requests in the 
             absence of a doHead() method.
        
 It is not required for servlets to override the 
             service() method to handle basic requests. 
             service() method delegates to other methods which
            are more practical to override
         
 HttpServlet supports GET, PUT, POST, HEAD, 
              DELETE, OPTIONS, and TRACE requests
    
HttpServlet request object methods: Java Servlet Specification, Version 2.4 (pgs 35)
    
         � getParameter: request.getParameter("name");
� getParameterNames
� getParameterValues: request.getParameterValues("name")[0];
� getParameterMap
 getParameterValues:returns an array of String objects
containing all the parameter values associated with a parameter name. getParameterMap:
returns a java.util.Map of the parameter of the request, which contains names as
keys and parameter values as map values.
    
  


Regular Expressions



    java.util.regex  provides APIs for pattern matching 
        with regular expressions
   
 java.util.regex API is most similar to that found in 
        Perl
   
 java.util.regex: Three important classes: Pattern, 
        Matcher, and PatternSyntaxException
   
 Pattern : no public constructors : must call one of 
        the public static compile methods to get a Pattern 
        object
   
 Matcher: To get a Matcher object call matcher method 
        on a Pattern object. No public constructor.
   
 PatternSyntaxException: regular expression pattern 
        syntax error. unchecked exception.
   
 Notice: matcher.find(),matcher.group(), 
        matcher.start(), matcher.end()
   
 Regular expression metacharacter: a character with 
        special meaning in a regular expression.
   
 Java meta characters: ([{\^-$|]})?*+.
   
 ! @ and # never carry a special meaning
   
 enforce a metacharacter to be treated as an ordinary character: precede the metacharacter with a backslash, enclose it within \Q (which starts the quote) and \E (which ends it)
  
 Character classes:





Character Classes


[abc]           

a, b, or c (simple class)


[^abc]
          
Any character except a, b, or c (negation)



[a-zA-Z]         
          
a through z, or A through Z, inclusive (range)


[a-d[m-p]]  
          
a through d, or m through p: [a-dm-p] (union)


 [a-z&&[def]] 

          
d, e, or f (intersection)


[a-z&&[^bc]] 
          
a through z, except for b and c: [ad-z] (subtraction)


[a-z&&[^m-p]] 
          

a through z, and not m through p: [a-lq-z] (subtraction)



 Simple Classes: [bcr]at, Negation: [^bcr]at, ranges:[a-c], union:[0-4[6-8]], Intersections:[0-9&&[345]], subtraction:[0-9&&[^345]]
Quantifiers:



    
 Quantifiers 
     Meaning

     Greedy 
     Reluctant 
     Possessive


     X? 
     X?? 
     X?+ 
     X, once or not at all

     X* 
     X*? 

     X*+ 
     X, zero or more times

     X+ 
     X+? 
     X++ 
     X, one or more times


     X{n} 
     X{n}? 
     X{n}+ 
     X, exactly n times

     X{n,} 

     X{n,}? 
     X{n,}+ 
     X, at least n times

     X{n,m} 
     X{n,m}? 

     X{n,m}+ 
     X, at least n but not
    more than m times
 Zero-length matches always start and end at the same index position
 [abc]+ (a or b or c, one or more times) or (abc)+ (the group "abc", one or more times)
 Greedy quantifiers: the matcher reads in, or eat, the entire input string prior to attempting the first match. If it fails, the matcher backs off the input string by one character and tries again, repeating the process until a match is found or there are no more characters left to back off from. 


Reluctant quantifiers: start at the beginning of the input string, then reluctantly eat one character at a time looking for a match. 


possessive quantifiers: always eat the entire input string, trying once (and only once) for a match. 

 Backreferences: To match any 2 digits, followed by the exact same two digits, you would use (\d\d)\1 as the regular expression: here \1 is the back reference to indicate to call the group(\d\d) one more time.
 


  
    
    
 Boundary Matchers
  

  
    
     ^
    
     The beginning of a line
  
  
    

     $
    
     The end of a line
  
  
    
     \b

    
     A word boundary
  
  
    
     \B
    
     A non-word boundary

  
  
    
     \A
    
     The beginning of the input
  
  

    
     \G
    
     The end of the previous match
  
  
    
     \Z

    
     The end of the input but for the final terminator, if any
  
  
    
     \z
    
     The end of the input

  
 

 pattern = Pattern.compile("[az]$", Pattern.MULTILINE | Pattern.UNIX_LINES);
 The quote(String s) method of the Pattern class, returns a literal pattern String for the specified String. Metacharacters or escape sequences in the input sequence will be given no special meaning.
 Matcher class methods: matches() requires the entire input sequence to be matched, while lookingAt does not
 Matcher class methods


Generics in Java



 

     Generics can prevent many run time errors.
    
 A generic class:
public class Box<T> {

    private T t; // T stands for "Type"          

    public void add(T t) {
        this.t = t;
    }

    public T get() {
        return t;
    }
}

Object creation:

Box<Integer> integerBox = new 

Box<Integer>();



 Generic method syntax: public <U> void 

inspect(U u){}
Type Erasure:Check this code:

public class MyClass<E> {
    public static void myMethod(Object item) {
        if (item instanceof E) {  //Compiler error
            ...
        }
        E item2 = new E();   //Compiler error
        E[] iArray = new E[10]; //Compiler error
        E obj = (E)new Object(); //Unchecked cast 

warning
    }
}



 


Basic Java But Essential Knowledge for exams like SCJA, or to the project managers new to Java technologies



 

    By definition an enumerated type is a finite set of 
        symbolic literals
   
 In Java an enumerated type is represented as 
        first-class object. 
   
 Enumerated type literals are allowed in case 
        statements. 
   
 The literals of an enumerated type may be of any 
        valid Java identifier
   
An interface may NOT contain any concrete method
       implementations
   
 An interface is NOT a class of any style. 
   
 An interface defines a set of abstract methods that 
       may have many implementations.
    
 An interface is NOT a member of a class.
    
 Both class associations and class compositions 
         relationship may be of any multiplicity. 
     
 compositions may also have navigation methods, but
          these methods must NOT pass references to the 
          owned objects. This is usually achieved by passing
          back a copy of the object rather than the owned 
          object itself. Composition implies that the owning
          object controls the life cycle of the owned bject.
     
 Dependency:one object uses another object during 
          computations.
     
 the portability of a Java application is NOT 
          dependent 
     
 upon whether information hiding was used. 
          the class cannot protect bad assignments. For 
          example, setting a negative value for an account 
          balance. 
      
 classes that do NOT support information hiding 
           are NOT treated specially in Java
      
 Disadvantages of information hiding: Access to 
           object 
       
 attributes incur a runtime penalty.However, the 
            Sun hotspot JVM usually can eliminate the added 
            overhead by "inlining" the methods where they 
            are called. 
       
 It is time consuming to use methods to access 
            object attributes rather than direct access.
       
 Information hiding does NOT restrict the 
            reusability of a superclass.
       
 Interfaces are only contracts (declarations of 
            public methods) and a program needs classes for 
            actual behavior. 
        
 NOT every class will have behavior that 
             requires an explicit contract (interface). 
        
It is the reference variables to objects that 
            need to be as generic as possible. This is the 
            essence of the "program to an interface" 
            principle. 
         
 An interface cannot be instantiated using the 
              new operator
         
 The minus symbol in a uml class diagram 
              signifies private visibility 
         
 the + symbol in a uml class diagram signifies 
              public visibility 
         
 encapsulation: all of its attributes be 
              private and it provides appropriate public 
              accessor and mutator methods. 
         
 UML: attribute representation: - attr : int 

UML
 
 ? is NOT a valid multiplicity indicator.
 
0..* indicates zero or more multiplicity.
 
0..1 indicates zero or one multiplicity, which is how 

you can represent an optional association.
 
?..1 is NOT a valid multiplicity indicator.


? is NOT a valid multiplicity indicator.
* is an abbreviation for 0..*.
M is NOT a valid multiplicity indicator.
? is NOT a valid multiplicity indicator.
0..* is exactly how to indicate zero or more.
M is NOT a valid multiplicity indicator.

Enums and arrays make use of object references 

A source file can have zero package statements or one 

package statement.


 A source file automatically imports all classes of its 

package.

java -version com.example.MyProgram: The Java 

interpreter prints the version information and exits.

The Collections APIs contain interfaces for lists and 

sets.

The Collections APIs are in the java.util package.

the classes for TCP and UDP communication are contained 

in the java.net package. 

cell phone side of an application requires the micro 

edition and the server side with EJB requires the 

enterprise edition

the J2SE platform has rich GUI capabilities, as well as 

IP communication capabilities allowing multiple, 

Internet-wide applications to exchange data. 

TCP/IP sockets are the basis of RMI.

RMI may create new threads for each request.

JMS is used to communicate with messaging services 

asynchronously. 

HTML does NOT provide interactive capabilities.

HTML does NOT provide a rich set of UI components.

HTML does provide navigation capabilities, such as 

hyperlinks.

HTML does provide rich text formatting capabilities, 

such as tables and cascading style sheets.

J2me include APIs for playing audio media.

J2ME provides limited user interface components.

J2ME applications usually execute on small devices with 

small screen resolution, which cannot support rich UI 

components. 

an Applet executes within a security sandbox that, by 

default, prohibits access to the user's filesystem. 

an Applet might fail to execute correctly (or at all) 

if the web browser does NOT have the appropriate JRE 

installed. 

an Applet does NOT have access to the web browser's 

cookie information.

the default security sandbox does permit communication 

with the originating enterprise server.

Applets execute in a security sandbox that does NOT 

permit access to files on the client system. 

Applets can be used to create animated games. However, 

Applets do NOT have access to gaming-specific APIs like 

J2ME applications do. 

Applets cannot connect to arbitrary Internet servers.

Applets may connect to the server that delivered the 

Applet to access media files on that server. 

Applets can access other Applets on the same web page.

Applets can access other Applets on the page through 

the AppletContext object supplied by the web browser.

Swing (Richest GUI components in j2SE) has a broader 

GUI component set than AWT. 

MIDP is a J2ME (not J2SE) profile. 

JSF is a J2EE web-based UI component framework with 

only a limited component set. 

AWT has a more limited GUI component set than Swing

SWT is NOT a standard J2SE technology.

JSP is used to create dynamic HTML content. It does NOT 

handle business logic. 

JMS is the technology that handles asynchronous 

requests and performs the business logic of these 

requests. 

JDBC is a database communication technology and does 

NOT handle business logic. 

JNDI is a naming and directory service interface. It 

does NOT handle business logic.

JNDI and JDBC support completely independent purposes 

in an application. JNDI is an interface to directory 

servers and JDBC is an interface to database servers. 

servlets and SQL support completely independent 

purposes in an application. Servlets respond to HTTP 

requests and SQL is used to communicate with relational 

databases. 

JavaMail uses SMTP (simple mail transfer protocol), 

which is used to send email from an application to 

users. 

JavaScript and EJB support completely independent 

purposes in an application. JavaScript provides 

interactivity to web pages and Enterprise JavaBeans 

provide business logic.

JSP technology simplifies the creation of dynamic web 

pages.

JSP technology is a server-side technology.

JSP technology is NOT intended to be used to create 

business components. 

JSP technology is ideal for web designers who are NOT 

familiar with Java programming. 

JSP technology is NOT an integration technology.

JSP is NOT an EJB technology

servlets are NOT an EJB technology

MDBs do NOT record client conversational state

stateful session beans are used to record client 

conversational state

stateless session beans do NOT record client 

conversational state

entity beans are used to represent persistent data. 

message-driven beans handle asynchronous events. 

Session beans only handle synchronous events. 

session beans represent business processes and 

stateless session beans are client-independent. That 

is, they do NOT store conversational state. 

session beans do NOT exist in the web container

stateless session beans are used to represent 

client-independent business processes.

J2EE provides a rich and flexible programming model, 

but it is NOT simple

J2EE infrastructure provides rich concurrency support 

in both the web and EJB tiers, which supports highly 

scalable application development. 

clustering is NOT directly supported by the J2EE 

specification. However, most vendor implementations of 

J2EE do support clustering. 

J2EE provides declarative transaction management.

declarative transaction management is a required 

feature of the EJB container

declarative user interface construction - is NOT part 

of the J2EE specification.

























































































 


Java Rules



 

     Do not synchronize an instance variable or a code block without an object - it is illegal in Java
    
 a synchronized context: wait(), notifyAll() - may be required to be called 
    
 Do not add a checked exception to an overridden 
         method
   
 A superclass does not have to be serializable, but its constructor will run when a serializable subclass instance is deserialized.
 	
Loose coupling: you can change the implementation of a class without affecting the other classes. For example, if two classes say A and B - do not use each other at all (no instantiation of the other or no method calling ), they are not coupled. If A uses B but B does not use A, then they are loosely coupled. If both A and B use each other, then they are tightly coupled.

Loose coupling expects that a class should keep its members private and that the other class should access them
through getters and setters 
 


Java Web-sites ad Forums




  theserverside.com
 
 javalobby.org
 javablogs.com
 jroller.com





Maven 1.0: A pretty good article: Compare Ant and Maven




   Maven 1.0 (Latest version is Maven 2.0)
 Maven 2.0
  Your first Maven project



Essential Knowledge on Web Component Development



  doGet() processes HEAD requests in the absence of a doHead() method
 Not the service() method but the methods that are called by the service method are better candidates for overriding 
HttpServlet supports GET, POST, DELETE, OPTIONS, and TRACE requests
 Retrieve a single value for a form parameter named "username": String u = request.getParameter("username");,
	String u = request.getParameterValues("username")[0]; 
 java.util.Enumeration getHeaderNames() - retrieves the complete collection of request headers

 set the content type of a servlet response: 

response.setContentType("text/html");

response.setHeader("Content-Type", "text/html"); 
 	
response.addHeader("Content-Type", "text/html"); 

 Servlet.destroy(): Servlets release resources: When called, the servlet container may not route other requests to that instance of the servlet: Servlet.destroy() may never be called
 The destroy() method, called by the web container when the servlet (or the web application) is being shutdown. This is a very good place to put the code to close related socket connection
 no guarantee on when the finalize() method will be called by the JVM
 The init() method is called by the web container before any HTTP requests are processed by the servlet. This is a good place to open a socket connection
 web.xml, JAR files, Class files, the deployment descriptor - are expected to be placed under WEB-INF directory
 A welcome file: used when a user requests a directory 
welcome files may be used at any directory level
 the default servlet is used to handle requests for specific files that exist in the webapp
 By default, the web container sends a 404 error back if the requested file does not exist
 Define a mime-mapping:

pdf
application/pdf

 WAR files are created using the jar command.
 A web application may be packaged into a WAR file for deployment, but it is not required. 
 The files within the WEB-INF directory and the files within the META-INF directory of a WAR file must not be directly served as content by the container in response to a Web client's request.
 A webapp can only have one web.xml file and all configuration must exist in that one file even if the Java class files exist in some other package
String boundObjectName = getServletContext().getInitParameter("com.example.BoundObj");:returns a String if an initializathttp://www.justetc.net/knowledge/editArticlesNext.php
http://www.justetc.net/knowledge/editArticlesNext.phpion parameter of that name exists in web.xml
session.removeAttribute("app.util.DataSource");: removes a session attribute
 Servlet context listeners are notified when the context is ready to process requests and when it is about to be shut down
 HttpSession.setAttribute(String attributeName,Object value): method stores an object


Servlet, JSP Specifications



   JSP Specification
  
 Servlet Specification
 Java Enterprise javabeans Specifications


JSP: Reference Manuals




   JSP Syntax : Quick Reference
  
 JSP Syntax : Quick Reference
'target='new'>JSP Syntax : Quick Reference - 2
 JSP tutorial by Sun: Reference




EJB 3.0: Specifications : Simplified API




  Focused on annotations - reduces the number of classes and interfaces, eliminates the need for a deployment descriptor
 Encapsulation of environmental dependencies and JNDI access: annotations, dependency injection, simple lookup mechanism
 Simpler enterprise bean types
 session beans: business interface can be a plain Java interface
 session beans: no need for a home interface
 entity persistence: Java Persistence API.
 A query language for Java persistence
 session beans and message driven beans: an interceptor facility
 implementation of callback interfaces is not a must
 Java persistence API: provide object relational mapping, can replace Hibernate
    
  A POJO (Plain Old Java Object) programming model
    
  A lightweight ORM persistence framework
    
  Dependency injection
    
  Metadata annotations
    
  Configuration by exception
    
  Elimination of component interfaces
    
  Elimination of home interfaces
    
  Reduction of the use of checked exceptions





A simple EJB 3.0 application: Explanation of EJB 3.0 technology: EJB => Spring Framework




    A simple EJB 3.0 application: Explanation of EJB 3.0 technology: EJB => Spring Framework



Java Design Patterns and Examples




  J2EE core design patterns: Click on a pattern rectangle to explore
 
 Data Access Object
 Transfer Object




Your First EJB Application



 

     Your first EJB application
    
 Your second EJB application
   
 An online music store - using EJB 3.0

 


Java Fundamentals



 

     An abstract class may have constructors
    
 It is illegal to invoke the new operator on an abstract class
 An abstract class is allowed to have method implementations
 There is no restriction about the placement of abstract classes in a class hierarchy
 It is legal for an abstract class to implement an interface and implement one or more interface methods
 A well-encapsulated class must have all of its attributes marked private
 A well-encapsulated class must hide all internal methods. 
 NOT all attributes require accessor or mutator methods
 


Java File Operation Example



   Code that helped me to create http://add.justEtc.net - the Bangladesh section based on the the web-site http://winnipeg.justEtc.net



package hello;

import javax.swing.JOptionPane;
import java.util.ArrayList;
import java.util.Iterator;
import java.io.*;

/**
 * Created by IntelliJ IDEA.
 * User: Sayed Ahmed
 * Date: May 30, 2008
 * Time: 9:45:08 PM
 * To change this template use File | Settings | File Templates.
 */

/**
Class containing major methods - operation methods
*/
class Process{
    private FileReader src = null; //source folder
    private FileWriter dest = null; //destination folder
    private ArrayList cityList = new ArrayList(); //arraylist to contain the names of all cities

    private String cityFileName; //reference to the file containing all city names
    private String folderToCopy; //path to the folder to be copied
    private String destination; // path  to the folder where the copy will be kept

    /**
     * Constructor
     */
    Process(){
//JOptionPane.showInputDialog(null,"City File Name");
        cityFileName = "C:\\test_development\\java\\resources\\cityList.txt";  
//JOptionPane.showInputDialog(null,"Folder to Copy");
        folderToCopy = "C:\\test_development\\java\\hello\\src\\resources\\source\\Winnipeg";  
//JOptionPane.showInputDialog(null,"Destination Path"); 
        destination = "C:\\test_development\\java\\hello\\src\\resources\\destination";         

        //load city list from the file to an arraylist
        copyCityList(cityFileName);

        //to create a file with links to all the cities of Bangladesh
        createFile();

        //copy a folder (winnipeg) and rename it to all the city names of Bangladesh -- one by one
        Iterator it = cityList.iterator();
        while(it.hasNext()){
            copyDirectory((String) it.next());
        }

    }

    /**
     * load city list into an ArrayList
     */
    private void copyCityList(String cityFileName){
        String city = "";
        try {
            BufferedReader bfCity = new BufferedReader(new FileReader(cityFileName));
            while(null != (city = bfCity.readLine())){
                cityList.add(city);
            }
        } catch (IOException e) {
            e.printStackTrace();  //To change body of catch statement use File | Settings | File Templates.
        } finally {
        }
    }

    /**
     * copy a folder , name the folder as the city name
     */
    private void copyDirectory(String city){
        try {
            copyDirectory(new File(folderToCopy), new File(destination+"/"+city), city);
        }catch (IOException e){
            e.printStackTrace();
        }
    }
    /**
     * Copies all files under srcDir to dstDir.
     * If dstDir does not exist, it will be created.
     * @param srcDir - folder to copy
     * @param dstDir - where to keep
     * @param city  - new folder name
     * @throws IOException
     */
    public void copyDirectory(File srcDir, File dstDir, String city) throws IOException {
        //if srcDirectory is a directory , create the directory
        if (srcDir.isDirectory()) {
            if (!dstDir.exists()) {
                dstDir.mkdir();
            }
            //if srcDir has child directories , create child directories - Recursively
            String[] children = srcDir.list();
            for (int i=0; i



Hello World: Web Service Application: IntelliJ, Tomcat, Apache Axis/Glassfish



This is an excellent document to start with. A sample server and a sample client are built in both Apache Axis and Glassfish


Skeleton of the Ant File



Ant can be used to compile and deploy Java applications. Struts and Spring applications also make use of Ant. Here, we have provided the structure of the build.xml file with examples that is used to carry out the functionalities. The redistribution of this file is in compatible with the copyright law of The Apache Foundation. 




<!--
     General purpose build script for web applications and web services,
     including enhanced support for deploying directly to a Tomcat 5
     based server.

     This build script assumes that the source code of your web application
     is organized into the following subdirectories underneath the source
     code directory from which you execute the build script:

        docs                 Static documentation files to be copied to
                             the "docs" subdirectory of your distribution.

        src                  Java source code (and associated resource files)
                             to be compiled to the "WEB-INF/classes"
                             subdirectory of your web applicaiton.

        web                  Static HTML, JSP, and other content (such as
                             image files), including the WEB-INF subdirectory
                             and its configuration file contents.

     $Id: build.xml.txt 565211 2007-08-13 00:09:38Z markt $
-->


<!-- A "project" describes a set of targets that may be requested
     when Ant is executed.  The "default" attribute defines the
     target which is executed if no specific target is requested,
     and the "basedir" attribute defines the current working directory
     from which Ant executes the requested task.  This is normally
     set to the current working directory.
-->

<project name="My Project" default="compile" basedir=".">



<!-- ===================== Property Definitions =========================== -->


<!--

  Each of the following properties are used in the build script.
  Values for these properties are set by the first place they are
  defined, from the following list:

  * Definitions on the "ant" command line (ant -Dfoo=bar compile).

  * Definitions from a "build.properties" file in the top level
    source directory of this application.

  * Definitions from a "build.properties" file in the developer's
    home directory.

  * Default definitions in this build.xml file.

  You will note below that property values can be composed based on the
  contents of previously defined properties.  This is a powerful technique
  that helps you minimize the number of changes required when your development
  environment is modified.  Note that property composition is allowed within
  "build.properties" files as well as in the "build.xml" script.

-->

  <property file="build.properties"/>
  <property file="${user.home}/build.properties"/>


<!-- ==================== File and Directory Names ======================== -->


<!--

  These properties generally define file and directory names (or paths) that
  affect where the build process stores its outputs.

  app.name             Base name of this application, used to
                       construct filenames and directories.
                       Defaults to "myapp".

  app.path             Context path to which this application should be
                       deployed (defaults to "/" plus the value of the
                       "app.name" property).

  app.version          Version number of this iteration of the application.

  build.home           The directory into which the "prepare" and
                       "compile" targets will generate their output.
                       Defaults to "build".

  catalina.home        The directory in which you have installed
                       a binary distribution of Tomcat 5.  This will
                       be used by the "deploy" target.

  dist.home            The name of the base directory in which
                       distribution files are created.
                       Defaults to "dist".

  manager.password     The login password of a user that is assigned the
                       "manager" role (so that he or she can execute
                       commands via the "/manager" web application)

  manager.url          The URL of the "/manager" web application on the
                       Tomcat installation to which we will deploy web
                       applications and web services.

  manager.username     The login username of a user that is assigned the
                       "manager" role (so that he or she can execute
                       commands via the "/manager" web application)

-->

  <property name="app.name"      value="myapp"/>
  <property name="app.path"      value="/${app.name}"/>
  <property name="app.version"   value="0.1-dev"/>
  <property name="build.home"    value="${basedir}/build"/>
  <property name="catalina.home" value="../../../.."/> <!-- UPDATE THIS! -->
  <property name="dist.home"     value="${basedir}/dist"/>
  <property name="docs.home"     value="${basedir}/docs"/>
  <property name="manager.url"   value="http://localhost:8080/manager"/>
  <property name="src.home"      value="${basedir}/src"/>
  <property name="web.home"      value="${basedir}/web"/>


<!-- ================== Custom Ant Task Definitions ======================= -->


<!--

  These properties define custom tasks for the Ant build tool that interact
  with the "/manager" web application installed with Tomcat 5.  Before they
  can be successfully utilized, you must perform the following steps:

  - Copy the file "server/lib/catalina-ant.jar" from your Tomcat 5
    installation into the "lib" directory of your Ant installation.

  - Create a "build.properties" file in your application's top-level
    source directory (or your user login home directory) that defines
    appropriate values for the "manager.password", "manager.url", and
    "manager.username" properties described above.

  For more information about the Manager web application, and the functionality
  of these tasks, see <http://localhost:8080/tomcat-docs/manager-howto.html>.

-->

  <taskdef name="deploy"   classname="org.apache.catalina.ant.DeployTask"/>
  <taskdef name="list"     classname="org.apache.catalina.ant.ListTask"/>
  <taskdef name="reload"   classname="org.apache.catalina.ant.ReloadTask"/>
  <taskdef name="undeploy" classname="org.apache.catalina.ant.UndeployTask"/>


<!--  ==================== Compilation Control Options ==================== -->

<!--

  These properties control option settings on the Javac compiler when it
  is invoked using the <javac> task.

  compile.debug        Should compilation include the debug option?

  compile.deprecation  Should compilation include the deprecation option?

  compile.optimize     Should compilation include the optimize option?

-->

  <property name="compile.debug"       value="true"/>
  <property name="compile.deprecation" value="false"/>
  <property name="compile.optimize"    value="true"/>



<!-- ==================== External Dependencies =========================== -->


<!--

  Use property values to define the locations of external JAR files on which
  your application will depend.  In general, these values will be used for
  two purposes:
  * Inclusion on the classpath that is passed to the Javac compiler
  * Being copied into the "/WEB-INF/lib" directory during execution
    of the "deploy" target.

  Because we will automatically include all of the Java classes that Tomcat 5
  exposes to web applications, we will not need to explicitly list any of those
  dependencies.  You only need to worry about external dependencies for JAR
  files that you are going to include inside your "/WEB-INF/lib" directory.

-->

<!-- Dummy external dependency -->
<!--
  <property name="foo.jar"
           value="/path/to/foo.jar"/>
-->


<!-- ==================== Compilation Classpath =========================== -->

<!--

  Rather than relying on the CLASSPATH environment variable, Ant includes
  features that makes it easy to dynamically construct the classpath you
  need for each compilation.  The example below constructs the compile
  classpath to include the servlet.jar file, as well as the other components
  that Tomcat makes available to web applications automatically, plus anything
  that you explicitly added.

-->

  <path id="compile.classpath">

    <!-- Include all JAR files that will be included in /WEB-INF/lib -->
    <!-- *** CUSTOMIZE HERE AS REQUIRED BY YOUR APPLICATION *** -->
<!--
    <pathelement location="${foo.jar}"/>
-->

    <!-- Include all elements that Tomcat exposes to applications -->
    <pathelement location="${catalina.home}/common/classes"/>
    <fileset dir="${catalina.home}/common/endorsed">
      <include name="*.jar"/>
    </fileset>
    <fileset dir="${catalina.home}/common/lib">
      <include name="*.jar"/>
    </fileset>
    <pathelement location="${catalina.home}/shared/classes"/>
    <fileset dir="${catalina.home}/shared/lib">
      <include name="*.jar"/>
    </fileset>

  </path>



<!-- ==================== All Target ====================================== -->

<!--

  The "all" target is a shortcut for running the "clean" target followed
  by the "compile" target, to force a complete recompile.

-->

  <target name="all" depends="clean,compile"
   description="Clean build and dist directories, then compile"/>



<!-- ==================== Clean Target ==================================== -->

<!--

  The "clean" target deletes any previous "build" and "dist" directory,
  so that you can be ensured the application can be built from scratch.

-->

  <target name="clean"
   description="Delete old build and dist directories">
    <delete dir="${build.home}"/>
    <delete dir="${dist.home}"/>
  </target>



<!-- ==================== Compile Target ================================== -->

<!--

  The "compile" target transforms source files (from your "src" directory)
  into object files in the appropriate location in the build directory.
  This example assumes that you will be including your classes in an
  unpacked directory hierarchy under "/WEB-INF/classes".

-->

  <target name="compile" depends="prepare"
   description="Compile Java sources">

    <!-- Compile Java classes as necessary -->
    <mkdir    dir="${build.home}/WEB-INF/classes"/>
    <javac srcdir="${src.home}"
          destdir="${build.home}/WEB-INF/classes"
            debug="${compile.debug}"
      deprecation="${compile.deprecation}"
         optimize="${compile.optimize}">
        <classpath refid="compile.classpath"/>
    </javac>

    <!-- Copy application resources -->
    <copy  todir="${build.home}/WEB-INF/classes">
      <fileset dir="${src.home}" excludes="**/*.java"/>
    </copy>

  </target>



<!-- ==================== Dist Target ===================================== -->


<!--

  The "dist" target creates a binary distribution of your application
  in a directory structure ready to be archived in a tar.gz or zip file.
  Note that this target depends on two others:

  * "compile" so that the entire web application (including external
    dependencies) will have been assembled

  * "javadoc" so that the application Javadocs will have been created

-->

  <target name="dist" depends="compile,javadoc"
   description="Create binary distribution">

    <!-- Copy documentation subdirectories -->
    <mkdir   dir="${dist.home}/docs"/>
    <copy    todir="${dist.home}/docs">
      <fileset dir="${docs.home}"/>
    </copy>

    <!-- Create application JAR file -->
    <jar jarfile="${dist.home}/${app.name}-${app.version}.war"
         basedir="${build.home}"/>

    <!-- Copy additional files to ${dist.home} as necessary -->

  </target>



<!-- ==================== Install Target ================================== -->

<!--

  The "install" target tells the specified Tomcat 5 installation to dynamically
  install this web application and make it available for execution.  It does
  *not* cause the existence of this web application to be remembered across
  Tomcat restarts; if you restart the server, you will need to re-install all
  this web application.

  If you have already installed this application, and simply want Tomcat to
  recognize that you have updated Java classes (or the web.xml file), use the
  "reload" target instead.

  NOTE:  This target will only succeed if it is run from the same server that
  Tomcat is running on.

  NOTE:  This is the logical opposite of the "remove" target.

-->

  <target name="install" depends="compile"
   description="Install application to servlet container">

    <deploy url="${manager.url}"
       username="${manager.username}"
       password="${manager.password}"
           path="${app.path}"
       localWar="file://${build.home}"/>

  </target>


<!-- ==================== Javadoc Target ================================== -->

<!--

  The "javadoc" target creates Javadoc API documentation for the Java
  classes included in your application.  Normally, this is only required
  when preparing a distribution release, but is available as a separate
  target in case the developer wants to create Javadocs independently.

-->

  <target name="javadoc" depends="compile"
   description="Create Javadoc API documentation">

    <mkdir          dir="${dist.home}/docs/api"/>
    <javadoc sourcepath="${src.home}"
                destdir="${dist.home}/docs/api"
           packagenames="*">
      <classpath refid="compile.classpath"/>
    </javadoc>

  </target>



<!-- ====================== List Target =================================== -->

<!--

  The "list" target asks the specified Tomcat 5 installation to list the
  currently running web applications, either loaded at startup time or
  installed dynamically.  It is useful to determine whether or not the
  application you are currently developing has been installed.

-->

  <target name="list"
   description="List installed applications on servlet container">

    <list    url="${manager.url}"
        username="${manager.username}"
        password="${manager.password}"/>

  </target>


<!-- ==================== Prepare Target ================================== -->

<!--

  The "prepare" target is used to create the "build" destination directory,
  and copy the static contents of your web application to it.  If you need
  to copy static files from external dependencies, you can customize the
  contents of this task.

  Normally, this task is executed indirectly when needed.

-->

  <target name="prepare">

    <!-- Create build directories as needed -->
    <mkdir  dir="${build.home}"/>
    <mkdir  dir="${build.home}/WEB-INF"/>
    <mkdir  dir="${build.home}/WEB-INF/classes"/>


    <!-- Copy static content of this web application -->
    <copy todir="${build.home}">
      <fileset dir="${web.home}"/>
    </copy>

    <!-- Copy external dependencies as required -->
    <!-- *** CUSTOMIZE HERE AS REQUIRED BY YOUR APPLICATION *** -->
    <mkdir  dir="${build.home}/WEB-INF/lib"/>
<!--
    <copy todir="${build.home}/WEB-INF/lib" file="${foo.jar}"/>
-->

    <!-- Copy static files from external dependencies as needed -->
    <!-- *** CUSTOMIZE HERE AS REQUIRED BY YOUR APPLICATION *** -->

  </target>


<!-- ==================== Reload Target =================================== -->

<!--

  The "reload" signals the specified application Tomcat 5 to shut itself down
  and reload. This can be useful when the web application context is not
  reloadable and you have updated classes or property files in the
  /WEB-INF/classes directory or when you have added or updated jar files in the
  /WEB-INF/lib directory.

  NOTE: The /WEB-INF/web.xml web application configuration file is not reread
  on a reload. If you have made changes to your web.xml file you must stop
  then start the web application. 

-->

  <target name="reload" depends="compile"
   description="Reload application on servlet container">

    <reload url="${manager.url}"
       username="${manager.username}"
       password="${manager.password}"
           path="${app.path}"/>

  </target>


<!-- ==================== Remove Target =================================== -->

<!--

  The "remove" target tells the specified Tomcat 5 installation to dynamically
  remove this web application from service.

  NOTE:  This is the logical opposite of the "install" target.

-->

  <target name="remove"
   description="Remove application on servlet container">

    <undeploy url="${manager.url}"
         username="${manager.username}"
         password="${manager.password}"
             path="${app.path}"/>

  </target>


</project>




  Licensed to the Apache Software Foundation (ASF) under one or more
  contributor license agreements.  See the NOTICE file distributed with
  this work for additional information regarding copyright ownership.
  The ASF licenses this file to You under the Apache License, Version 2.0
  (the "License"); you may not use this file except in compliance with
  the License.  You may obtain a copy of the License at

      http://www.apache.org/licenses/LICENSE-2.0

  Unless required by applicable law or agreed to in writing, software
  distributed under the License is distributed on an "AS IS" BASIS,
  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  See the License for the specific language governing permissions and
  limitations under the License.


Java Connector Overview and an Example




 Java Connector Architecture (JCA) enables integration of the J2EE components to any Enterprise Information Systems (EIS). EIS can be heterogeneous where scalability is a must. 
 JDBC assumes DBMS/RDBMS in the back-end, JCA targets any kind of EIS.
 One of the key parts of JCA is the Resource Adapter - usually a part of the application servers. Multiple resource adapters can be used to connect to different EISs of heterogeneous types.
 When resource adapters are plugged into the Application Servers they provide necessary transaction, security, and connection pooling mechanisms
 In the JCA, an application contract defines the API that provides the client view to access EISs. The API can be EIS/resource adapter specific or standard.
 Common Client Interface (CCI) - a set of interfaces and classes that allows J2EE applications to interact with heterogeneous EISs.
 Example of JCA 

   EJBs, Servlets can connect to EISs through CCI and then access the EISs as required
 J2EE SDK provides a black box resource adapter that we will use in our example to connect to EISs. We will assume RDBMS as the EIS in the example
 Example: The flow of the application: client->servlet->resource adapter->EIS Tier 
(RDBMS - stored procedure)
 In a servlet example: first step: import javax.resource.cci.*;
 javax.resource.cci.*; - for ResourceException class
 import cci blackbox classes: import com.sun.connector.cciblackbox.*;
 Also, import servlet and application specific classes
 
public class ExampleServletConnector extends HttpServlet{
   private Connection con;
   private ConnectionFactory cf;
   private String user;

  public void init() throws ServletException{
      try{
            //establish JNDI interface
            InitialContext ic = new InitialContext();
           //look up user and password
           user = (String) ic.lookup("java:comp/env/user");
           String password = (String) ic.lookup("java:comp/env/password");
          //reference to the connection factory 
for the CCI black box resource adapter - 
coded name CCIEIS
          cf = (ConnectionFactory) ic.lookup("java:comp/env/CCIEIS");
         //collect connection specification, connect to the database
         ConnectionSpec conSpec = new ConnectionSpec (user,password);
       con = cf.getConnection(conSpec);
      }catch(ResourceException rex){
         rex.printStackTrace();
      }catch(NamingException nex){
        nex.printStackTrace();
      }
  }

 Now define the doGet method for processing. An example doGet method is as follows
 
public void doGet(HttpServletRequest req, HttpServletResponse res) 
throws ServletException {
  PrintWriter output = null;
  res.setContentType("text/html");
  try{
     PrintWriter out = res.getWriter();
     //find the number of rows in the account table - 
check getAccountAccountCount method in the next item
     int accCount = getAccountAccountCount();
     out.println("Account Count" + accCount);
  }catch(Exception ex){
   ex.printStackTrace();
  }
}

 getAccountAccountCount() method: to query the database and determine the number of rows in the account table


public int getAccountCount(){
   int count = -1;
   try{
       Interaction ix = con.createInteraction();
       CciInteractionSpec iSpec = new CciInteractionSpec(); 
       iSpec.setSchema(user); 
       iSpec.setCatalog(null); 
       //stored procedure name to calculate the number of rows
       iSpec.setFunctionName("ACCOUNTCOUNT");
       RecordFactory rf = cf.getRecordFactory();
       IndexedRecord iRec = rf.createIndexedRecord("InputRecord");
       Record oRec = ix.execute(iSpec, iRec);
       Iterator it = ((IndexedRecord)oRec).iterator();
       //process
        while(it.hasNext()){
          Object obj = it.next();
          if (obj instanceof Integer){
             count = ((Integer) obj).intValue();
          }else if (obj instanceOf BigDecimal){
           count = ((BigDecimal) obj).intValue();
          }
        }
   }catch(Exception ex){
   }
   return count;
}


 




EJB Overview: EJB in a nutshell




   Objects provide encapsulation/re-usability at the class level. 
  
 A component can be comprised of multiple objects 
  
 Component = logical groups of classes = distributed objects = business objects
  
 A component can be developed to address a specific enterprise applications. 
  
 Hence, components can provide significant encapsulation/re-usability in the partitioned enterprise problems.
  
 Component model = components + their environments + contracts for interaction
  
 EJB is a server side component model. Used to create application server side components
  
 Most sophisticated application server = CTM = Transaction Processing Monitors + Object Request Brokers = J2EE Servers
  
 EJB components: entity, session, message-driven
  
 Entity beans = real world objects = business objects = data objects = customers = products = may be contained as records in the database = persistent
 
 Multiple clients can access entity beans concurrently
 
  Session beans = processes + tasks. Example: the act of reserving a ticket = to control work flow = to handle a series of tasks carried out by the entity beans = can also access/(help to access) data = do not represent data = transient = after the task is done - no need to maintain states = do not need to support concurrent access
 Message-driven beans = stateless beans = no component interface = respond to client requests = clients place requests through JMS = support concurrent client access = can be used to perform tasks and manage interactions among beans = asynchronous = request and response two separate processes, RMI = synchronous




Accessing EJBS from Servlet




   EJBs can be used to create enterprise applications like banking systems. Clients will interact with such systems for operations like: withdraw cash, transfer cash, pay bills
 When clients directly access EJBs it poses concerns such as: security risks, firewall blocking, EJB architecture becomes transparent to the clients
 Servlets can act as the middleman between the EJBs and clients.

  Change to EJB becomes easier - hidden from the user
 
 Data in EJB better protected
 
 Central control of EJBs 

 When servlets work as the proxy, smaller devices become capable to access EJBs through http protocol (light weight protocol - good for smaller devices ) 
 Servlets can work as a front controller
 Supports different types of clients
 Better separation of responsibilities that is desirable - web: flow control logic, EJBs: business logic, EIS: Enterprise Information Systems
 Remember: servlets can be bottlenecks here, better servlet design strategy is required - synchronization may help
 For small applications - may be overkill


How to use EJBs from servlets 


  Think about a banking system implemented in EJBs. 
 Entity beans = Customers, Accounts 
 Session beans = operations like withdraw cash
 In this scenario, servlets can call the session beans and return the results to the clients
 A sample servlet to access the EJBs: Here remote ejbs are assumed : EJB2 is assumed : just example is shown - the coding style may not be great ... just an example

// for remote references to objects such as EJBs
import javax.rmi.PortableRemoteObject;
//banking system ejb package
import bankingSystemEjbClasses.*;
import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
import javax.naming.*;

public class ServletEjb extends HttpServlet{
   public void doGet(HttpServletRequest request, HttpServletResponse response) 
throws IOException, ServletException{
  float credit = 10;
  float debit = 20;
  String custName = "";
  float initBalance = 0, endBalance = 0;

  try{
      //locate and instantiate the account manager bean
      Context context = new InitialContext();
      Object ref = context.lookup("AccountManager");
      AccountManagerHome accountManagerHome = (AccountManagerHome) 
PortableRemoteObject.narrow 
(ref, AccountManagerHome.class);
      AccountManager accountManager  = accountManagerHome.create(); 

//create a savings account and manipulate it
accountManager.createSavingsAccount(1,"John Smith")  
initBalance = accountManager.getInitialBalance("1");

//create customer
accountManager.createCustomer(1,"John Smith")  
custName = accountManager.getCustomerName();

//generate output
response.setContentType("text/html");
PrintWriter out = response.getWriter();

out.println("<html>");
out.println("<body>");
out.println("Customer Name:" + custName);
out.println("Initial Balance:" + initBalance);

out.println("</body>");
out.println("</html>");


  }catch(Exception ex){
}

}
}






Servlet Random Information



  

      Web component information sharing: web context (ServletContext), request, session, and page
     
 ServletContext - Scope: entire web-application (Servlets & JSPs)
     
 page/PageContext : A single point of access for many of the attributes of a JSP page 
     
 For each access of the servlet a thread is created. In applications a thread can be accessed concurrently by many threads.
     
 If the servlet accesses and edits some external resources, then data inconsistency, and  data loss may occur
     
 Synchronized access should help:
     
 public class TestServlet extends HttpServlet implements SingleThreadModel   will provide synchronization and concurrency
      
 In JSP, you can include <%@ page isThreadSafe="false" %> - to provide thread safety
      
 For SingleThreadModel: you still have to synchronize access to class variables and to any shared resources that are stored outside the servlet. example:
 
 synchronized(sharedResource) {
 }


       
 For high-traffic servlets, you should use explicit synchronization blocks rather than implementing SingleThreadModel
 Synchronization is only an issue if the servlet accesses external data resources -- returns data from another source: not for a servlet that just performs a task with no data access
  


Java 2 Security Architecture




Security Services Provide
   
    Data Integrity
   
 Data Confidentiality
   
 Access Control - Authentication and Authorization
   

 Encryption helps to provide such security services

Core Java Security Architecture

   -- Core Java 2 Security Architecture
  
 -- Java Cryptography Architecture (JCA)
  
 -- Java Cryptography Extension (JCE)
  
 -- Java Secure Socket Extension (JSSE)
  
 -- Java Authentication and Authorization Service
  
 -- JCE and JSSE extends JCA



 JCA - Platform Packages

 java.security - core security classes and interfaces
 java.security.cert - certificate management
 java.security.interfaces - Interfaces used to manage DSA and RSA keys
 java.security.spec - key specification, algorithm parameter specification


 JCA - not useful for data encryption 
 JCE provides the data encryption
 JCE packages: javax.crypto, javax.crypto.interfaces, 
javax.crypto.spec

 JSSE includes a Java implementation of SSL and Transport Layer Security (TLS) - server authentication, message integrity, optional client authentication.

 JSSE Packages:
javax.net.ssl,
javax.net,
javax.security.cert


 JAAS : limit access to resources based on user identity. JAAS implements PAM (Pluggable Authentication Module Framework)   - user-based, group-based, 

role-based access control

  JAAS packages:
javax.security.auth,
javax.security.auth.callback, 
javax.security.auth.login,
javax.security.auth.spi

 Core Security 

 java.security.Permission, PermissionCollection, Permissions  - specify level of access to resources in J2EE applications

 Permissions - sets of diverse permissions

 Permission Example:

 Permission has many subclasses like FilePermission, SerializablePermission, SocketPermission, NetPermission
 FilePermission prm = new FilePermission("c:\\test.img","read,write");

 Security Policy - list permissions in files
System Policy - jre/lib/security/java.policy file
User Policy - java.policy file under user's directory

 Java 2 has a policy tool under [JAVA_HOME\bin\policytool]- GUI based - to create/edit policy files - type policytool in the command prompt


 Java Security Manager - determines whether requests to the access valued resources should be allowed? - core java security classes also ask security manager 

 For access permission check

 Access Controller controlls access to critical system resources. Security Manager calls Access Controller methods to delegate tasks


 J2EE Application Security


 J2EE Role Based Security

 J2EE applications can contain both protected and unprotected resources. Access to the protected resources can be controlled using authorization mechanisms.

 Authorization
 
  Identification : recognize an entity - device or person 
 
 Authentication : process to identify
 

 Role based security:
 create logical privileges known as roles - may be based on customer/user/job profile

 Users are grouped together into the roles - same role users into the same role group

 Creating roles for J2EE Applications:
Create roles, associate them with an application, WAR file, JAR files

 At the time of deployment, the deployer maps roles to the security identities


 Principle: identity assigned to a user or group after authentication

 A tool named deploytool can be used to add users and groups to a J2EE server.

 You can get J2EE and deploytool at: http://java.sun.com/javaee/downloads/index.jsp

 In deploytool
menu->tools->server configuration->select users from left -> select reals from right ->

 Provide ID/Password for the user. Assign a group to the user. - Rest will be common sense, play with the tool

 You can also use realmtool to add users and groups
example: realmtool -add 5006 5006admin admin,staff
Syntax: -add user password groups
add, import, userGroups

 Under deployment tool, afterwards, you can apply permissions to the different applications. You can also view and modify the descriptor file from : menu->tools>view configuration.




J2EE:Java EE Code Samples & Apps



 

      Java EE Code Samples & Apps
 


J2EE Architecture: J2EE Design Patterns: Related Concepts



  

     Design Patterns
   
      What are design patterns? Design patterns are  
specific/(context-based) solutions/approaches to address specific problems/situations. Some problems are general/open problems and very common problems in a particular type of applications. Design patterns can be created to solve such problems in a specific context and that can be re-used every time that type of situations arise. Design patterns help designers to easily communicate their ideas (in a common concept). 
 Benefits: Proven solution to a specific problem, saves time as you don't have to come up with an original solution each time you encounter a particular problem  
  
 Design patterns can be applied at different levels of abstractions such as, Analysis, Architectural, Behavioral, Creational, Design, and Structural
  
 J2EE patterns are mostly for design and architecture purpose and for three architectural tiers: Presentation, Business, and Integration

 J2EE Applications: Client Tier (Clients for J2EE Applications): Design Issues

   J2EE supports many types of clients. Hence, you need to decide which types of clients you want to make use of. Also, based on the clients you need to decide how to solve a specific problem. Design patterns can be client-specific and problem-specific
  
 J2EE clients: laptops, desktops, palmtops, and cell phones. 
 Connection Mechanisms (to J2EE Applications): an intranet, the Internet, a wireless network, a wired network, and a combination of wired and wireless networks 
  
 Clients can be thin, server dependent, browser based, rich, and stand-alone
 Client design issues: Concerns: which types of clients to use, should more than one type of clients be supported?, network types to support, security considerations, platform considerations, and unreliability of networks
 
 Clients should: Connect to the network on an ad-hoc basis, transmit minimum amount of data, should consider situations when firewalls may block particular protocols, mobile clients should consider that they have small display screens and limited resources
 
 More design issues for J2EE clients: Logic for user interface presentation, validate user inputs, communicate with the server using a common protocol, maintain the conversational state
 Browser clients - design issues: can not function independently of the server, easy to design and implement, widely available, well-familiar to the users, provide  limited functionality, can perform user input validation, servers can also do the validation, uses HTTP protocol, needs to maintain conversational states using Cookies, URL rewriting, or server side session
 Java clients - design issues: 
Client types: applications, applets, MIDlets are the Java client options 
 Applications like usual desktop applications - can run offline, use JFC/Swing for user interface, provide richer user experience, more responsive than thin clients, use less bandwidth than browser clients, and can create fewer connections than browser clients 
 Applets run mostly under browsers, use JFC/Swing for user interface 
 MIDlets are mostly for small applications for cell phones, two-way pagers, and palmtops - use MIDP user interface APIs
 Java clients (Applications, applets, MIDlets) can handle most user input validation and hence, reduce network overhead, can connect to J2EE applications, directly to the web tier (using HTTP though face some complexity of translation), EJBs, EISs, 
 Applets and applications can connect to EJBs directly,  
Java clients can access EIS tier directly (not recommended as it would bypass J2EE server and transaction management)
 Java clients have the facility to cache and manipulate large amounts of state in memory and manage session effectively 
 
 Web Tier

   Servlets, and JSPs are web-tier component
  
 Manage the interaction between web-clients and the 
       application's business logic.
   
 Output from this tier: mostly HTML and XML content
   
 Business logic can be implemented entirely here, though, enterprise beans are recommended
   
 Servlets should be used to: implement web-application logic, generate binary content, act as a web-tier controller
   
 JSPs are better suited to generate static HTML text
   
 JSP Purpose: produce structured textual content, generate XML messages, act as templates
  
 In JSP, custom tags are more desirable than scriptlets. Why? scriplets - not reusable, mix logic with content, make JSP pages difficult to read and update, errors can be difficult to interpret, difficult to test (including unit testing)
 Web-Tier Application Framework

   Many web-tier application requirements are not met by the actual J2EE platform. A framework working on top of J2EE can meet these requirements such as, dispatching requests, invoking model methods, and compiling views.
 
 Making use of existing ready-built and proven application framework is recommended than creating your own [it takes time and may be all your designs will not be the best]
 Some frameworks: J2EE blueprints Web Application Framework, Apache Struts, JavaServer Faces

 Model View Controller (MVC)

   Well-suited for interactive applications such as web-applications.
  
 Divides applications into three modules - model, view, controller
  
 model: data representation and business logic, view: data presentation and user input, controller: controls information flow
 
 Benefits: separation of design and implement, decreased code duplication, centralized control
 Servlets are ideal as controllers
 Controllers receive all incoming client requests and direct them to the appropriate business logic component, after processing the requests, the controller selects the right view to return to the client.   

 Model 1 and Model 2

   Model 1: No controller, direct access to the JSP pages, decentralized application, simpler and hence suited for small and static applications
  
 Model 2: Uses a controller, are favored as they are easy to maintain and extend, provide a single point for security and logging


 EJB Tier
 
    Hosts business logic of a J2EE application
   
 Provides system level services to the business components
   
 Developers can focus on business-logic problems
   
 J2EE platform handles the system related problems (complex many times) such as, state maintenance, transaction management, and availability to local and remote clients
  
 EJBs provide a good interface between presentation components in the web-tier and business data and systems in the EIS tier
  
 EJBs - entity, session, message driven
  
 EJBs can provide remote or local access by providing remote or local interfaces. EJBs are mostly designed for distributed environments and hence typically provide remote interfaces
 
 When to use entity beans: for business objects when it represents persistent data and requires persistent storage, multiple client access, data access in portable manners, server managed transaction handling is preferable
 
 Entity beans: Persistence can be managed by yourself or by the EJB container 
 
 When to use Stateful Session-beans: for client centric business logic, business objects are short-lived, and non-persistent. Works for the client to maintain conversational state
 When to use Stateless session beans: Provide server side behavior, do not maintain states for a specific client,  good for reusable  service objects, to minimize resources  and support a large number of clients, when the business object does not operate on instance variables.
 
EIS Tier

 J2EE EIS technologies: J2EE Connectors to integrate J2EE applications with existing EISs using resource adapters - synchronous
 
 Java Message Service: To be used with enterprise messaging systems - asynchronous
 
 JDBC - integrates J2EE applications with relational database systems
 
 asynchronous: high quality and reliable message-delivery service, provide higher volume of messaging, more work for the developers
 
 synchronous - suitable to handle two or more EISs synchronously.

  


Core J2EE Component Technologies



Core J2EE Component Technologies
 

     J2EE Application Components: Web Components, Business Components
    
 Web-Component: 
     
      Software entity hosted by a web-container on a J2EE Server
     
 Generate user interface for web-based applications
     
 Two Types: Servlets, JSPs
     
 Servlets: Process requests dynamically, format responses
    
JSPs: How to process requests, and format responses
    
   
 Business Components: EJB Components or enterprise beans: Contain business logic of an enterprise application. Three types: Session Beans, Entity Beans, Message Beans
 



J2EE Services
 

     Distributed Communication Services:
    
       Distributed Communication Services provide J2EE components distributed communications capability and EIS access
      
 Web-container Service Components: JMS, JNDI, RMI-IIOP,CORBA and Java

       IDL
      
 Roughly: RMI-IIOP, CORBA and Java IDL: Applet and Application Container to Web-Container Communications  
      
 JMS, JNDI: Between web-container and EJB container components. For application components not for users
      
 JNDI: Naming and directory services.
      
 CORBA: Objects to communicate regardless of their implementation language or the operating system
      
 Java IDL API enables J2EE applications to utilize CORBA functionality
      
    
 Other support technologies
     
         JDBC, Java Transaction API, Java Transaction Service, J2EE Connectors, JavaMail 
        
 JDBC: Provides database access from Java.
        
 Latest JDBC: Provides connection pooling and distributed transaction support for the J2EE platform  
        
 JDBC Drivers: Java, Partial Java, Java Native Interface (JNI)
        
 J2EE connector architecture provides supports to connect to EISs 
        
 JavaMail API to handle mailing 
     
 


Distributed J2EE Applications



  

      Single tier applications are easier to design. Single tier applications mix data, presentation, business logic altogether. It is easier design but workload distribution becomes difficult. Moreover, software maintenance becomes a big headache.
    
 Multi-tier applications can address these challenges. Here, the application, hence, the workload is divided into multiple modules - tiers. The presentation, data, business logic can be separated from each other. This provides well organized software development. The workload can be divided among several developers more effectively. Also, software maintenance becomes easier.
   
 Multitiered Applications Benefits:
    
        Availability: Accessible at all times - more accessible. Move parts of your applications into separate machines
       
 Extensibility: Ability to add more capabilities. Can add more capabilities without breaking the systems
       
 Scalability: Support more users: Add extra computing resources to each layer, 
       
 Reliability: Maintain the accuracy and integrity of the data. Separating business logic from the rest of the applications, grouping operations into transactions
        
 Maintainability: Ability to update software code  
    
    
 Design considerations for Distributed Applications/Systems
      
            Event handling: Generation and notification of distributed events
           
 Persistence: How distributed objects are stored and accessed
           
 Concurrency: Acquiring and releasing locks in distributed environments
           
 Security: Mechanisms to provide distributed authentications, authorization, encryption, and auditing
           
 Transactions:
           
 Language dependencies
           
 Platform dependencies : Provide seamless operations irrespective of the underlying OSs or processors 
      
    
 Distributed object management issues:
     
          Create and delete distributed objects
         
 Reliable communications among distributed 
              objects 
         
 Provide interfaces for object mapping
         
 Activating distributed objects and binding 
              them to names
          
 Advertising and accessing objects and 
               services 
     
     
 Design distributed systems:
     
         Partition the problem into modular 
        
 Make the module small enough to be individually solvable 
        
 Findout the application and communication layers/requirements

     
      
 Transaction Management
       
          
       
  


Creating Java Development Environment with Struts for Your Home PC



  

      Why Struts?
          
              Just take a look at the web-sites using Struts 
            
 J2EE does not meet all the requirements for web-applications. Struts addresses these requirements.
            
 Check this article for details
          
     
 Components Required
     
          J2SE 5/6 or J2EE 5 - both JRE and JDK
         
 Tomcat 5.5/6 - web-server
         
 Apache Struts
         
 Eclipse development IDE [optional]
         
 Ant build tool [optional]
     
     
 Download Links
     
          J2SE 5/6 
         
 J2EE 5 - both JRE and JDK
         
 Tomcat 5.5/6 - web-server
         
 Apache Struts
         
 Eclipse development IDE [optional]
         
 Ant build tool
     
     
 Key Steps
      
          Install the software
         
 Set environment variables like: JAVA_HOME, JRE_HOME, ANT_HOME, CATALINA_HOME, CLASSPATH
         
 Configure them
         
 Deploy and test a sample application
      
  


Step By Step Video Tutorial: Struts-based Java Web Application Development



  

       Step By Step Video Tutorial: Struts-based Java Web Application Development
  


Struts 2 vs. Struts 1



Please check the following resources:
  

 Struts 2: Configuration Elements


     
 Struts 1 vs Struts 2

 Migrating from Struts 1 to Struts 2

 Comparing Struts 1 and 2






  


Key J2EE  Components : Basic Concepts with Examples




   Java EE 5 (J2EE 5) uses XML deployment descriptors for the configuration of the web-applications and web-components.
 
 What Java EE provides? It provides the internal framework/structure/system level capability/system-level infrastructure to support large enterprise level applications with features like distributed database, distributed computing , security, and transaction management.
 
 J2EE also provides specifications for Containers, Connectors, Interfaces, Communications among different components for enterprise applications
 
 J2EE is J2SE based, it supports all of J2SE
 
J2EE in addition to Swing and AWT introduces JSF for user interface creations
 
 Sun provides the J2EE specifications and a reference implementation. Anyone can re-implement the complete specification. Hence, if you develop applications based on the core J2EE, it should be compatible across different vendors who later re-implemented J2EE.
 However, J2EE does not cover 100% of the requirements of all types of enterprise applications, hence vendors usually add values/extra features to their implementations.
 J2EE provides multi-tier application development
Elements of J2EE

   Clients: Fat Clients: A console application, and JFC, Swing, AWT based GUI applications. Thin clients: Browser based client applications
 
 Servers: Connect client components to the business logic.
 
 Server side components: Web-Components: JSPs, Servlets. Business components: EJBs.
 
J2EE containers provide the support/framework/infrastructure for these server side components. Web Container contains JSPs/Servlets. EJB Container contains EJBs

 Some concepts in J2EE 


   Containers, JSF, JDBC, XML Support, Web-Services, Transaction Management, Security
 Servlet: Mostly for Processing/calculations: From The clients, you can refer to a Servlet for example in HTML Form Actions. The Servlet runs in the server, does required processing and returns HTML web-page to the clients.
 JSP: Mostly for user interfaces, can also include processing using Java codes
 JSF: JSF is used to create rich user interfaces in conjunction with JSPs and Servlets.
 JSF provides API based server side user interface creation
 JDBC provides APIs to access relational databases. Enterprise applications very often will store information in databases. JDBC helps to access these information.
 EJBs evolved on RMI's limitations to support enterprise applications. EJB components contain business logic.
 EJBs are of three types: entity beans, session beans, message beans

J2EE 5 XML Support Technologies

 
    JAXP: DOM based processing. SAX: Stream based processing
    
 JAXB: Mapping between XML and Java classes
    
 JAXR: XML Registries
    
 JAXM for messaging
    
 JAX-RPC: XML based RPC
    
 JAXR, JAXM, and JAX-RPC: provide support for SOAP and web-services 
 
 
 Web-services: Here functions/operations are provided as web-based services. Others can call and make use of these services. Great for B2B communications and integrations.
  
Web-services: Related concepts: WSDL: Describes the services provided - Web Service Description Language. Service Registries such as ebXML, UDDI. JAXR API can access these registries. SOAP: The protocol for communications (web-services).
 Transaction Management: Java EE including EJBs provides transaction management support.
 J2EE also provides security supports such as role-based authorization, both declarative and programmatic securities.



JSF: Lesson - 1: JSF Specifications



 Video Demonstration of a sample JSF application create: Read the article first
  
      JSF Specifications
    
 JSF is not standalone technology, you have to use it in conjunction with JSPs, Servlets, EJBs
    
 How to use JSF with Servlets and EJBs: In Servlet or EJB, explicitly create instances of UI components and use the UI classes directly
   
 JSF with JSPs: Use the JSF custom tag library with JSP 
   
 To use JSF, you need to understand JSF lifecycle: take a look at JSF Lifecycle: Restore view, Apply request values, Process validations, Update model values, Invoke application, Render response
  
 How to install JSF: Current version of Sun's Application Server contains JSF and JSTL
  
 For Tomcat 5.5:
  
      Download JSF from http://java.sun.com/j2ee/javaserverfaces/download.html and  JSTL from http://jakarta.apache.org/taglibs/doc/standard-doc/intro.html. 
  
 Put these Six JSF JARs into your project WEB-INF/lib  folder or tomcat lib folder: commons-beanutils.jar, commons-collections.jar, commons-digester.jar, commons-logging.jar, jsf-api.jar, and jsf-impl.jar
 Download JSF Jars
 
 Put these two JSTL JARs in the same way: jstl.jar and standard.jar
   
 
 JSF provides different custom actions as will be provided below:
 
 You can use these elements/controls/actions to collect user data, to display output, to validate user inputs, control the flow of the application dynamically/statically also, convert data from one type to another.

 HTML Custom Actions

Input: To create input elements

h:inputHidden, h:inputSecret,
h:inputText, h:inputTextarea



Output:create output elements
h:message, h:messages,
h:outputFormat, h:outputLabel,
h:outputLink, h:outputText


Selection: Create selection elements like combo boxes
h:selectBooleanCheckbox,
h:selectManyCheckbox,
h:selectManyListbox,
h:selectManyMenu,
h:selectOneListbox,
h:selectOneMenu,
h:selectOneRadio


Commands: Create form submission buttons or links

h:commandButton,
h:commandLink


Miscellaneous

h:dataTable, h:form,
h:graphicImage, h:panelGrid,
h:panelGroup, h:column 
 JSF Core custom actions: 


Converters:Standard

f:convertDateTime,
f:convertNumber, f:converter


Listeners:Listener for a component

f:actionListener,
f:valueChangeListener


Miscellaneous

f:attribute, f:loadBundle,
f:param, f:verbatim
	


Selection

f:selectItem, f:selectItems


Validators:Standard

f:validateDoubleRange,
f:validateLength ,
f:validateLongRange ,
f:validator


View: Create JSF view or sub-view

f:facet, f:subview, f:view	
An example of JSF with JSP with Managed Bean Support


   You need a configuration file like faces-config.xml , or you can use any other file but you have to supply the file name in the web.xml file.
 To use a managed bean, you need to define a managed bean in the JSF configuration file with a name, class, and scope
 Also you need to define navigation rules in the configuration file. A navigation-rule defines the start page, a condition, and which page to navigate to when the condition occurs
 Create the managed bean class
 In your JSP, you should refer to the JSF tag libs and JSTL tag libs by 



 <%@ taglib uri="http://java.sun.com/jsf/core" prefix="f" %> 

 <%@ taglib uri="http://java.sun.com/jsf/html" prefix="h" %>  

 Then in the JSP page you will be able to use the JSF tags and the managed beans directly
 A sample example with code
 Video Demonstration of the example JSF application create 
 Details about other JSF features like: using managed beans, controlling page navigation, accessing JSF context data in beans, converting data, validating user inputs, using message bundles to support internationalization will be disucssed in another article.


  


JSF: Lesson - 2: JSF Managed Beans



 Codes for this article 

Video Demonstration for this article
 

      Target: Intermediate level programmers and web-developers. Any programmer/web-developer can take a look.
    
 Pre-requisite: HTML, JSP, Servlet, Tomcat, J2EE, MVC, and 
    JSF Introduction. Check the corresponding sections of this web-site, to have an idea on the required technology knowledge
   
 Pre-requisite: Download this sample JSF application
   
 Beans used by JSF enabled applications are called managed beans as they are created and managed by JSF
   
 JSF is based on the MVC architecture where beans provide the models
    
 To be used with JSF, a bean must have a no argument constructor. The bean can expose its properties with get or set methods for reading or writing from outside 
    
 Beans can be used in two ways in JSF applications: The information required to create managed beans are provided in the configuration file (faces-config.xml), JSF uses value binding expressions or method binding expressions, to refer to the properties of the managed beans.
   
 Configuring Managed Beans
   
       Beans are configured in the faces-config.xml file. The file is usually provided under WEB-INF folder. Though from the web.xml file (using the javax.faces.CONFIG_FILES context parameter), you can refer to any other file where the configuration is provided.
      
 META-INF/faces-config.xml file can also be used  
      
 Multiple configuration files can also  be used. The file names should be mentioned in the web.xml file.
      
 Initialize Bean Properties
         
              Tags such as, value, null-value, list-entries, map-entries can be used to initialize bean properties in the configuration file. value can be used to set String type parameter, null-value is used to set an Object type property to null, list-entries is used to initialize a List type property, map-entries is used to initialize a Map type property. Check this file for examples - the target audience I assume have the background to understand it just by checking
         
         
 Accessing Bean properties
           
               Bind managed bean methods to expressions in JSP pages
              
  <h:inputText value="#{bus.origination}" size="35"/> or <h:inputText value="#{bus["origination"]}" size="35"/>  : set flight property as the control is a JSF input control
            
 <h:outputText value="#{bus["origin"]}" size="35"/> or <h:outputText value="#{bus.origin}" size="35"/>: Retrieve value from the origin property. 
            
 Access list property values: #{bus.times["1"]}
            
 Access Map property values: flight.airportNames.key, 
flight.airportNames[key]
             
 Similarly, you can also bind managed bean methods to expressions in JSP pages.
           
   

 


JSF: Lesson - 3: Controlling Page Navigation in JSF



   

       Sample application for this article
      
 Video Tutorial for this article
      
 Pre-requisite:  JSF Lesson 1 & 2
      
 Navigation: Two Types:
      
           Static: The destination page is fixed
          
 Dynamic: The destination page varies with the conditions
      
      
       Static 
      
       Static: You provide a fixed value for the "action" attribute for a JSF event control/action element
      
 That fixed value is mapped to the fixed destination page in the configuration file such as the faces-config.xml 
      
 If you check our previous lesson, the searchForms.jsp contains . In this line, the text 'action="submit"' defines the static navigation.
       
 The navigation rule in the following text maps submit action to searchResults.jsp page [static/fixed mappping]

 <navigation-rule>

      <from-view-id>/searchForm.jsp</from-view-id>

      <navigation-case>

         <from-outcome>submit</from-outcome>

         <to-view-id>/searchResults.jsp</to-view-id>

         <redirect/>

      </navigation-case>

   </navigation-rule>


       
       
      
 Dynamic Navigation
      
          In this case, the action takes a dynamic value. All possible values are mapped into [different] destination pages. Hence, when the action gets a different value, the destination page is also different [unless mapped to the same destination page]
        
 To get dynamic nature, the action is mapped to a value/property or a method of a managed bean. The property must be of String type. Also, the method must return String and must not take any parameter.
      
 At the time, the action is executed [the button is pressed], corresponding property value is retrieved or the method is called to get value. This value is then matched with the navigation cases in faces-config.xml. 
     
 The user is then redirected to the destination of the mathching navigation case.  
     
 Example: Binding action to a value/method expression in jsp:       . Here, search is a method in the bus bean. Hence, at the button click, the search method is executed. For example, it may get values such as success, noTrips
 
 Mapping in faces-config.xml: success, and noTrips are mapped in the following navigation cases.
 
 

 <navigation-rule>

    <from-view-id>/searchForm.jsp</from-view-id>

    <navigation-case>

      <from-outcome>success</from-outcome>

      <to-view-id>/searchResults.jsp</to-view-id>

      <redirect/>

    </navigation-case>

    <navigation-case>

      <from-outcome>noTrips</from-outcome>

      <to-view-id>/noTrips.jsp</to-view-id>

      <redirect/>

    </navigation-case>

  </navigation-rule>

       
      
     
 Navigation Rules:
     
         If you observe the navigation rules above, you will notice <from-view-id> elements. This is to mention, from where the action is generated.
        
 <from-outcome>: is the action message based on which flow is maintained
        
  <to-view-id> element provides the destination page
         
 <from-view-id> is optional. If you omit <from-view-id>, then for all <from-outcome> message for the application, will be redirected to the  related <to-view-id> destination page. If all page refers to the same privacy policy file, this rule can be useful
        
Example: 

<navigation-rule>

  <navigation-case>

    <from-outcome>privacy-policy</from-outcome>

    <to-view-id>/WEB-INF/privacy.jsp</to-view-id>

  </navigation-case>

</navigation-rule>

 You can also redirect for the same <from-outcome> message for a group of pages to the same destiation. Such as: 


<from-view-id>/order/*</from-view-id>

<from-outcome>success</from-outcome>

<to-view-id>/WEB-INF/invoice.jsp</to-view-id>

 <from-action> element: Consider a case, in the same page, in two command buttons, the actions are mapped to save and search methods. Both save and search methods can return success as the  element. But, if you want them (two successes from the two methods) to go to two different destination pages, then <from-action> element comes handy.
 You can use <from-action> element in the following way:

<navigation-rule>

  <from-view-id>/searchForm.jsp</from-view-id>

  <navigation-case>

    <from-action>#{bus.search}</from-action>

    <from-outcome>success</from-outcome>

    <to-view-id>/searchResults.jsp</to-view-id>

  </navigation-case>

  <navigation-case>

    <from-action>#{bus.save}</from-action>

    <from-outcome>success</from-outcome>

    <to-view-id>/searchForm.jsp</to-view-id>

  </navigation-case>

</navigation-rule>

     
   
 Now check the sample example and the video.    
   


JSF: Lesson - 4: Accessing Context Data from Beans



  

      In some cases, from the beans used in JSF applications, you will need to access the request parameters. For example, in the BusSearch.java, we accessed, the request parameters [Please check the previous JSF lesson]. 
 How to access: FacesContext context = FacesContext.getCurrentInstance();
   
 Some methods of FacesContext: 
   	
	 Map getApplicationMap()
	
 String getInitParameter(java.lang.String name)
	
 Map getInitParameterMap()
	
 String getRemoteUser()
	
 Map getRequestCookieMap()
	
 Map getRequestHeaderMap()
	
 Map getRequestHeaderValuesMap()
	
 Map getRequestMap()
	
 Map getRequestParameterMap()
	
 Iterator getRequestParameterNames()
	
 Map getRequestParameterValuesMap()
	
 Map getSessionMap()

 Sample code:
FacesContext context = FacesContext.getCurrentInstance();
Map requestParams = 
      context.getExternalContext().getRequestParameterMap();
    String tripNum = (String) requestParams.get("tripNum");


  


JSF: Lesson - 5: Converting Data





  
      
  

      Sample application for JSF Data Type Converter
           
 Video Tutorial for JSF Data Type Converter
      
 Pre-requisite:  JSF Lesson 1, 2, 3, 4
     
 JSF provides two different types of built-in data type converters such as: String and Date Conversion, Number and String Conversion.
     
 Related tags: f:convertDateTime, f:convertNumber, f:converter 
     
 In our previous examples, we could accept departing and returning dates to be date/time types rather than string types [as expected]
    
 How to achieve: 


<h:inputText id="departDate" value="#{bus.departDate}">
  <f:convertDateTime pattern="MM/dd/yy"/>
</h:inputText>
<h:message for="departDate"/>


 For other types of conversions, you have to use custom converters. 
 To make use of the strategy, you have to write a class that will do the conversion work.
 Your class should implement: javax.faces.convert.Converter interface that has two methods that you must implement. One method takes input as String and returns an Object. Another method, takes an Object as the input and returns String.
 Methods 

Object getAsObject(javax.faces.context.FacesContext context,
   javax.faces.component.UIComponent component, java.lang.String value)
String getAsString(javax.faces.context.FacesContext context,
   javax.faces.component.UIComponent component, java.lang.Object value)

 getAsObject: Returns an object
 getAsString: Returns String
 As you have access to the JSF context, and the corresponding user interface component in these methods
- you will be able to greatly customize your converter
 How to use the custome converter:

    Define a converter in the configuration file (faces-config.xml) as follows where TerminalConverter is your custom converter class:
<converter>
<converter-id>terminal.converter</converter-id>  
<converter-class>
net.justetc.jsf.TerminalConverter
</converter-class>
</converter>

 From JSPs refer to a converter-id as defined in the configuration file. See example below:


	<h:inputText value="#{bus.origin}">
	  <f:converter converterId="terminal.converter"/>
	</h:inputText>
or

	<h:inputText value="#{bus.origin}" converter="terminal.converter"/>



 You can also, define/use the converter for all properties of a class such as Terminal as follows:

<converter>  
<converter-for-class>
net.justetc.jsf.Terminal
</converter-for-class>  
<converter-class>net.justetc.jsf.TerminalConverter
</converter-class>
</converter>




 In this last scenario, whenever JSF identifies a Terminal type data it converts the data using the TerminalConverter class. 

   <h:inputText value="#{bus.origin}"/>


In this example, as it encounters bus.origin to be of Terminal type, it will convert the origin to be a Terminal object though the user will just enter a String.







  


JSF: Lesson - 6: Validating User Input in JSF



  

      Target: Intermediate level web-developers. 
     
 Sample application for this article
      
 Video Tutorial for this article
     
 In web-application development, validating user inputs 
          takes much efforts. JSF has made validations much easier than usual
      
 JSF Built-in Validators:
      
           validateDoubleRange: Checks that the value 
provided is a double value. You can also set a minimum and a maximum. 
          
 validateLongRange: Validates the input to be a long. It also has the optional minimum and maximum parameters.
           
 validateLength: Validates the length of a string 
       
 Without the minimum and the maximum values these validators actually do nothing
        
       
 You can also enforce a value as follows. If no value is provided, an error message is displayed 
<h:inputText id="origin" value="#{bus.origin}" size="35" required="true"/>

 You can also create your own custom validator that should implement javax.faces.validator.Validator interface.
 You have to implement the validate() method: validate(FacesContext arg0, UIComponent arg1, Object arg2)
    throws ValidatorException
 In the error condition, you should throw ValidatorException from the validate method
 Then you need to register the custom validator in the faces-config.xml file using a id as follows:
<validator>
    <validator-id>currency.validator</validator-id>
    <validator-class>net.justetc.jsf.CurrencyValidator</validator-class>
  </validator>

 From your JSP, you can refer to the validator as follows:

  
<h:inputText id="salary" value="#{employee.salary}">              
              <f:validator validatorId="currency.validator"/>
            </h:inputText>

  


JSF: Lesson - 7: Using Message Bundles in JSF: Support Internationalization




 Target: Intermediate level web-developers (Java-platform). 
 Sample application on Internationalization with JSF
 Video Tutorial on Internationalization with JSF 
 To support Internationalization, in the web-pages,  the text messages and the control texts make use of the keys for the values/messages. In the value fields, keys are  mentioned/provided as the values. Later, based on the current locale/language, the keys are replaced with the appropriate texts for the current locale/language
 In some property files, keys and their corresponding values are listed
 For each language, one property file is provided
 The file names usually end with .properties
 Example: contents of the Property files:
search.text.new=New Search
orderBtn.text = Confirm Order

 Wherever orderBtn.text is used for values, will be replaced with "Confirm Order"
 If the file name is messages.properties, the file can be loaded into the JSP pages as follows:
<f:loadBundle basename="net.justetc.jsf.messages" var="msgs"/>

 Example use of the property file from JSP pages
<h:outputText value="#{msgs.orderBtn.text}"/>

 You are also required to list the default languages (that your application supports) in the faces-config.xml file



Java: Struts: Lesson 5: Processing Requests with Action Objects



Corresponding Video Tutorial

Code Example for this article


   What happens? When a form is submitted? 
  
 Flow: 
   
       Refer to a x.do from form action 
      
 Check struts-config.xml for action named 'x' 
      
 Check the corresponding  type (class) of the action, execute the execute method of that action type (really a class where execute is the class method) 
      
 The method will usually return a string using mapping.findForward("string"), 
  
 Then the string will be matched in struts-config.xml file in the global forwards section or as part of the actions. 
 In forwards a string is mapped to a destination web-page/action

 Steps to write a simple application [one programmer]: 

Create the first web-page with the form [html/jsp]
Create an action for the action string of this form in struts-config.xml file [mention the type/class, and corresponding forwards and specify the destination] 
 The destination of a forward can be another action, forwards can be part of the action or can be placed in the global forwards section, 
 Write the class and the corresponding execute method
In the execute method you may require to collect the user supplied values/inputs, process the data and return a string using mapping.findForward based() on your logic/requirements. 
Create the destination pages.




Lesson 6: Handling Request Parameters with Form Beans



Training Video for this article 

Code used for this article



  

      In jsp pages, you can create forms with html form tag or html:form tag
Form Beans concept

    You can use request.getParameter() to retrieve data from a form from the backend/server side. Or you can create a bean based on the form parameters/values. Then from the server side, you can retrieve values from these beans.
  
 From server side, you can set output values to the request object directly or you can create a bean to carry output messages to the next step and set the output bean in the request/session object.
 In the output jsp pages, you can use bean:write or jsp expression language to print those output/result bean values [provided that output values are set into a bean in the server side]
 How to declare form beans: Just define a simple Java class that extends ActionForm and then declare it in the struts-config.xml file with form-beans tag

 Steps in creating a struts application. This example will follow the same rules

 Modify the struts-config.xml file: declare the form beans, map incoimg .do to action classes, map all possible return strings from action calsses to destination pages
 Write the class for the bean that extends ActionForm. Write all the getter and setter methods, write reset method [useful for session scoped beans], write validate method for form input validation
 Create the result/output beans. You do not need to declare them in struts-config.xml file
 Define the action class to handle requests and return the right forward string that also need to be mapped in the config file
 Create the input pages that calles the actions
 Write output jsp pages

Character Classes
`[abc]`	a, b, or c (simple class)
`[^abc]`	Any character except a, b, or c (negation)
`[a-zA-Z]`	a through z, or A through Z, inclusive (range)
`[a-d[m-p]]`	a through d, or m through p: [a-dm-p] (union)
`[a-z&&[def]]`	d, e, or f (intersection)
`[a-z&&[^bc]]`	a through z, except for b and c: [ad-z] (subtraction)
`[a-z&&[^m-p]]`	a through z, and not m through p: [a-lq-z] (subtraction)

Quantifiers			Meaning
Greedy	Reluctant	Possessive	Meaning
`X?`	`X??`	`X?+`	`X`, once or not at all
`X*`	`X*?`	`X*+`	`X`, zero or more times
`X+`	`X+?`	`X++`	`X`, one or more times
`X{n}`	`X{n}?`	`X{n}+`	`X`, exactly `n` times
`X{n,}`	`X{n,}?`	`X{n,}+`	`X`, at least `n` times
`X{n,m}`	`X{n,m}?`	`X{n,m}+`	`X`, at least `n` but not more than `m` times

Boundary Matchers
`^`	The beginning of a line
`$`	The end of a line
`\b`	A word boundary
`\B`	A non-word boundary
`\A`	The beginning of the input
`\G`	The end of the previous match
`\Z`	The end of the input but for the final terminator, if any
`\z`	The end of the input

Search Engines
Robots (Search Engines)(Major) Make sure and submit to these. Aeiwi Alexa AltaVista AOL Netfind Anzwers Canada.com Direct Hit EuroSeek Excite Find What Google HotBot ICQ It I Won InfoMak InfoSeek Lycos MSN Search Northern Light NBCi Surf Gopher Thunderstone UKMax WebCrawler World Search Center What-U-Seek Indexes & Catalogs (Major) Submit to these critical directories manually so nothing is left to chance. Britannica LookSmart ComFind Jayde LookSmart Lycos (directory) Netscape Search Open Directory Project Pronet Rex Snap! TurnPike What's New Too Yahoo Yellow Pages Robots (Smaller Search Engines) A2Z Solutions Diabolos Fathead Final Search Funky Cat Galaxy GlobeTech Matilda MaxBan National Directory Neftem NetSearch Search It The Cozy Cabin Web Search 2K WhatUseek World Search Center Indexes & Catalogs (General) ABAT NZ CanLinks CyberDirectory Dewa Discover it DirectFind EarthFind EgyptWeb ELaud FetchDog Find It FindLink Frequent Finders Global Page http://www.gohip.com/ HandiLinks Hits Galore ICN iExplorer Infohiway InfoSpace JumpCity LifeStyle UK LinkMaster MasterSite NerdWorld NTT Directory Omnisearch PeekABoo PlanetClick PointGuide QuestFinder Scrub The Web SearchBlazer SearchHound SearchKing SearchMode SelectSurf SiteShack SplatSearch Starting Point theNet1 WebIndex WebScout WebSleuth WhatsNu WebVenture Hotlist Yep Indexes & Catalogs (General Business Related) 411Locate 411Now AE Business Exchange BizCardz BizWeb Business Seek Comfind InfoMarket LinkStar OZOnline ProNet QuickPage WebDirect USA Online

Operators	Precedence
postfix	`expr++ expr--`
unary	`++expr --expr +expr -expr ~ !`
multiplicative	`* / %`
additive	`+ -`
shift	`<< >> >>>`
relational	`< > <= >= instanceof`
equality	`== !=`
bitwise AND	`&`
bitwise exclusive OR	`^`
bitwise inclusive OR	`\|`
logical AND	`&&`
logical OR	`\|\|`
ternary	`? :`
assignment	`= += -= *= /= %= &= ^= \|= <<= >>= >>>=`

abstract	do	import	public	transient
boolean	double	instanceof	return	try
break	else	int	short	void
byte	extends	interface	static	volatile
case	final	long	super	while
catch	finally	native	switch
char	float	new	synchronized
class	for	package	this
continue	if	private	throw
default	implements	protected	throws

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