Direct Web Remoting

indexadjustmentInternet and Web Development

Nov 13, 2013 (3 years and 5 months ago)

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DWR:
Direct Web Remoting

Rajesh R


rajeshranganathan@cevalsoft.com



DWR:Agenda


What is DWR?


Why DWR?


Reverse AJAX


Advantages

What is DWR?



Is a Java and JavaScript open source library which
allows you to write Ajax web applications



Specifically designed with Java technology in mind


> “Easy AJAX for Java”




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?



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



DWR comes with some JavaScript utility functions

Ingredients


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


Reverse Ajax is the biggest new
feature in DWR 2.0


It gives you the ability to
asynchronously send data from a web
-
server to a browser.


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


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.

Advantages


Call Java Functions like RMI or Soap


Automatically create Java versions of
JS


Expose business methods through JS

Supported Environment


DWR requires JDK1.3 or later


Tomcat


Weblogic


Websphere


Jboss


Etc…

Browser Support


Firefox 1.0 and above


Internet Explorer 6.0 and above


Opera 8.0 and above


Safari 1.3 and above

Queries

Thanks!



Rajesh