DWR: Direct Web Remoting Hussain Fakhruddin [email_address]

About Me Open Source Advocate Believe in coding with style Blogger (hussulinux.blogspot.com)‏ Pure Vegetarian

Open Source Advocate

Believe in coding with style

Blogger (hussulinux.blogspot.com)‏

Pure Vegetarian

DWR:Agenda What is DWR? FAQ Advantages Tutorial

What is DWR?

FAQ

Advantages

Tutorial

DWR: Definition Easy Ajax for Java. Export your Java code to a browser and include the results in your pages.

Easy Ajax for Java. Export your Java code to a browser and include the results in your pages.

DWR:Definition In other words its nothing but An RPC library which makes it easy to call Java functions from JavaScript and to call JavaScript functions from Java (a.k.a Reverse Ajax).

In other words its nothing but An RPC library which makes it easy to call Java functions from JavaScript and to call JavaScript functions from Java (a.k.a Reverse Ajax).

Some features Virtually any data-structure between Java and Javascript (including binary file uploading and downloading) exception handling advanced CSRF(Cross site request forgery) protection Integration with Spring and Guice

Virtually any data-structure between Java and Javascript (including binary file uploading and downloading)

exception handling

advanced CSRF(Cross site request forgery) protection

Integration with Spring and Guice

JS to Java

Java to JS: Reverse Ajax allows Java code running on the server to find out what clients are viewing certain pages, and to send to them JavaScript, generated either manually or using a Java API

allows Java code running on the server to find out what clients are viewing certain pages, and to send to them JavaScript, generated either manually or using a Java API

Ingredients A Java Servlet running on the server that processes requests and sends responses back to the browser. JavaScript running in the browser that sends requests and can dynamically update the webpage

A Java Servlet running on the server that processes requests and sends responses back to the browser.

JavaScript running in the browser that sends requests and can dynamically update the webpage

Dynamic JS DWR generates dynamic JS based on the Java Classes The DWR Engine then does some Ajax magic to make it feel like the execution is happening on the browser, but in reality the server is executing the code and DWR is marshalling the data back and forwards.

DWR generates dynamic JS based on the Java Classes

The DWR Engine then does some Ajax magic to make it feel like the execution is happening on the browser, but in reality the server is executing the code and DWR is marshalling the data back and forwards.

Advantages Call Java Functions like RMI or Soap Automatically create Java versions of JS Expose business methods through JS

Call Java Functions like RMI or Soap

Automatically create Java versions of JS

Expose business methods through JS

Tutorial Calculator Example What you need? Eclipse Step by Step Run

Calculator Example

What you need?

Eclipse Step by Step

Run

Calulator Example We will write a Java class which has the following methods int add(int a, int b); int subtract(int a , int b); int divide(int a, int b); int multiply (int a, int b);

We will write a Java class which has the following methods

int add(int a, int b);

int subtract(int a , int b);

int divide(int a, int b);

int multiply (int a, int b);

What you need? Download DWR.jar from : http://getahead.org/dwr/download

Download DWR.jar from :

http://getahead.org/dwr/download

Add the Jar

Add Dependency Apache Commons: http:// commons.apache.org/downloads/download_logging.cgi

Apache Commons: http:// commons.apache.org/downloads/download_logging.cgi

Add Jars to Project

Edit the web.xml <servlet> <servlet-name>dwr-invoker</servlet-name> <servlet-class>org.directwebremoting.servlet.DwrServlet</servlet-class> <init-param> <param-name>debug</param-name> <param-value>true</param-value> </init-param> </servlet> <servlet-mapping> <servlet-name>dwr-invoker</servlet-name> <url-pattern>/dwr/*</url-pattern> </servlet-mapping>

Write your Business Logic package org.hussulinux.samples; public class Calculator { public Calculator() { } public int add( int a, int b) { return a + b; } public int subtract( int a, int b) { return a - b; } public int multiply( int a, int b) { return a * b; } public float divide( int a, int b) { if (b == 0) { return 0; } else return ( float )(( float )a / ( float )b); } }

Add dwr.xml along with web.xml <!DOCTYPE dwr PUBLIC &quot;-//GetAhead Limited//DTD Direct Web Remoting 2.0//EN&quot; &quot;http://getahead.org/dwr/dwr20.dtd&quot;> <dwr> <allow> <create creator=&quot;new&quot; javascript=&quot;Calculator&quot;> <param name=&quot;class&quot; value=&quot;org.hussulinux.samples.Calculator&quot;/> </create> </allow> </dwr>

Open Default page to check

Create front end

index.jsp <!DOCTYPE html PUBLIC &quot;-//W3C//DTD HTML 4.01 Transitional//EN&quot; &quot;http://www.w3.org/TR/html4/loose.dtd&quot;> <html> <head> <meta http-equiv=&quot;Content-Type&quot; content=&quot;text/html; charset=ISO-8859-1&quot;> <title>My First DWR Example</title> <script type='text/javascript' src='/CalculatorDWR/dwr/interface/Calculator.js'></script> <script type='text/javascript' src='/CalculatorDWR/dwr/engine.js'></script> <script type='text/javascript' src='/CalculatorDWR/dwr/util.js'></script> </head> <body> A:<input type =&quot;text&quot; id=&quot;a&quot;><br/> B:<input type =&quot;text&quot; id=&quot;b&quot;><br/> <hr/> <br/> <input type =&quot;button&quot; value=&quot;Add&quot; onClick=&quot;Calculator.add(a.value,b.value,replyfunc)&quot; ><br/> <input type =&quot;button&quot; value=&quot;Subtract&quot; onClick='Calculator.subtract($(&quot;a&quot;).value,$(&quot;b&quot;).value,replyfunc);' ><br/> <input type =&quot;button&quot; value=&quot;Multiply&quot; onClick=&quot;Calculator.multiply(a.value,b.value,replyfunc)&quot; ><br/> <input type =&quot;button&quot; value=&quot;Divide&quot; onClick=&quot;Calculator.divide(a.value,b.value,replyfunc)&quot; ><br/> <script type=&quot;text/javascript&quot;> var replyfunc=function(data){ if (data!=null && typeof data=='object')‏ alert(dwr.util.toDescriptiveString(data,2)); else dwr.util.setValue(&quot;answerdiv&quot;, dwr.util.toDescriptiveString(data,1)); } </script> <hr/> Answer = <div id =&quot;answerdiv&quot;> </div> </body> </html>

<!DOCTYPE html PUBLIC &quot;-//W3C//DTD HTML 4.01 Transitional//EN&quot; &quot;http://www.w3.org/TR/html4/loose.dtd&quot;>

<html>

<head>

<meta http-equiv=&quot;Content-Type&quot; content=&quot;text/html; charset=ISO-8859-1&quot;>

<title>My First DWR Example</title>

<script type='text/javascript' src='/CalculatorDWR/dwr/interface/Calculator.js'></script>

<script type='text/javascript' src='/CalculatorDWR/dwr/engine.js'></script>

<script type='text/javascript' src='/CalculatorDWR/dwr/util.js'></script>

</head>

<body>

A:<input type =&quot;text&quot; id=&quot;a&quot;><br/>

B:<input type =&quot;text&quot; id=&quot;b&quot;><br/>

<hr/>

<br/>

<input type =&quot;button&quot; value=&quot;Add&quot; onClick=&quot;Calculator.add(a.value,b.value,replyfunc)&quot; ><br/>

<input type =&quot;button&quot; value=&quot;Subtract&quot; onClick='Calculator.subtract($(&quot;a&quot;).value,$(&quot;b&quot;).value,replyfunc);' ><br/>

<input type =&quot;button&quot; value=&quot;Multiply&quot; onClick=&quot;Calculator.multiply(a.value,b.value,replyfunc)&quot; ><br/>

<input type =&quot;button&quot; value=&quot;Divide&quot; onClick=&quot;Calculator.divide(a.value,b.value,replyfunc)&quot; ><br/>

<script type=&quot;text/javascript&quot;>

var replyfunc=function(data){

if (data!=null && typeof data=='object')‏

alert(dwr.util.toDescriptiveString(data,2));

else

dwr.util.setValue(&quot;answerdiv&quot;, dwr.util.toDescriptiveString(data,1));

}

</script>

<hr/>

Answer = <div id =&quot;answerdiv&quot;> </div>

</body>

</html>

Run

Queries

Thanks! Joe Walker for starting this as open source project TIBCO for supporting this project You can email me at: [email_address] Visit: http://hussulinux.blogspot.com

Joe Walker for starting this as open source project

TIBCO for supporting this project

You can email me at: [email_address]

Visit: http://hussulinux.blogspot.com