BANGALORE, INDIA: The Rich Internet Applications have been the result of Web 2.0 where the primary focus was on user interactivity. Flash has always been a great tool to add interactivity to websites. Adobe's Flex has helped designers and developers to build a variety of engaging RIAs that look and feel the same across different browsers and OSes.

However, user interactivity was limited within Flash application, be it a website or a desktop application. To counter this, BlazeDS comes to the rescue. This helps connect Flex platform applications to connect with server-side Java web applications.

About BlazeDS
BlazeDS is one of the several Open-Source projects hosted by Adobe. It is server-based technology used for integration between Flex and Java. For connecting Flex to Java, BlazeDS runs on Java application servers as servlets, which allows you to use it with any standard Java web application. It enables remote procedure calls and message exchanges between Flex and Java platforms, and hence helps developers to couple Flash platform based interfaces with robust enterprises servers.

BlazeDS uses ActionScript Message Format (AMF) protocol, which is somewhat similar to SOAP. But AMF protocol is a binary protocol and hence is faster than SOAP. When Adobe released BlazeDS, it also published AMF specification that allows BlazeDS and Java to communicate with the Flex clients using a compact binary format. Even the existing Java code can be integrated with Flex applications -be it Flash or AIR, with help of BlazeDS.

In this article we'll see how we can develop a simple Flex RIA and integrate it with Java server side using BlazeDS. We will be creating a Flex RIA project having BlazeDS using Eclipse.

Getting started
With this month's DVD we have provided the BlazeDS binary distribution. You would need to download Adobe Flex Builder 3.0.2 Professional Eclipse plug-in form http://bit.ly/6ZBF5. To get started with building the RIA, the prerequisite to be installed is JDK version 5 or higher and Eclipse 3.3 or higher on a Windows platform. Though Flex Eclipse plug-in requires Eclipse version 3.3 or higher, it works on Eclipse 3.2.2 onwards till Eclipse 3.4 (Ganymede), whereas for Eclipse Galileo (version 3.5) it does not install directly.

To install BlazeDS, just extract the zipped BlazeDS file to a location, say C:\BlazeDS. The extracted contents will contain a 'war' file named as 'blazeds.war'. Now install the downloaded Flex plug-in for Eclipse with installer FB3_WWEJ_ plugin.exe. During the installation process, the installer prompts for Eclipse installation directory and once that is supplied, the installation proceeds to install the Flex builder plug-in into Eclipse. After installation is completed, we are all set to create Flex application using Eclipse.

While creating a new Flex project in Eclipse, select app server type as J2EE & app type as Web App which will be based on Flash platform.