Transcript DWR: Direct Web Remoting

DWR: Direct Web Remoting
Rajesh R
[email protected]
DWR:Agenda
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What is DWR?
Why DWR?
Reverse AJAX
Advantages
What is DWR?
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Is a Java and JavaScript open source library which
allows you to write Ajax web applications
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Specifically designed with Java technology in mind
> “Easy AJAX for Java”
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Allows JavaScript code in a browser to use Java
methods running on a web server just as if they
were in the browser
> Why it is called “Direct remoting”
Why DWR?
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Without DWR, you would have to create many Web
application endpoints (servlets) that need to be
address'able via URI's
What happens if you have several methods in a
class on the server that you want to invoke from the
browser?
> Each of these methods need to be addressable via URI whether
you are using XMLHttpRequest directory or client side only toolkit
such as Dojo or Prototype
> You would have to map parameters and return values to HTML
input form parameters and responses yourself
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DWR comes with some JavaScript utility functions
Ingredients
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A Java Servlet running on the server
that processes incoming DWR
requests and sends responses back to
the browser.
JavaScript running in the browser that
sends requests and can dynamically
update the webpage
JS to Java
Reverse Ajax
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Reverse Ajax is the biggest new
feature in DWR 2.0
It gives you the ability to
asynchronously send data from a webserver to a browser.
Java to JS: Reverse Ajax
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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
Dynamic JS
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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
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Call Java Functions like RMI or Soap
Automatically create Java versions of
JS
Expose business methods through JS
Supported Environment
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DWR requires JDK1.3 or later
Tomcat
Weblogic
Websphere
Jboss
Etc…
Browser Support
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Firefox 1.0 and above
Internet Explorer 6.0 and above
Opera 8.0 and above
Safari 1.3 and above
Queries
Thanks!
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Rajesh