Setting up Flex BlazeDS in FlashBuilder

One of the most compelling aspects of Flex is its ability to integrate with a wide variety of data sources. Many of the introductory tutorials online teach how to connect to http services to pull data. The result is typically an XML response. Flex makes it easy to manage XML but there are better ways. using XML requires an object on the server to be serialized to a text format which adds processing time. The response is also larger due to the variety of XML tags that need to be added in order to properly represent the object’s structure. Yes I hear you in the back telling me that JSON is a lighter weight response that doesn’t require all the tags. Regardless the response still needs to be parse out in the client. Finally the contract between client and server is not well defined with straight XML or JSON. Web services do provide a strict contract for the interface that the client can rely on but  the objects are still serialized with extraneous tags used to define the structure.

BlazeDS utilizes AMF to provide direct links between client and server objects. AMF provides access to objects through a binary protocol and eliminates the need to add additional tags that identify the object structure. It also reduces the work in flex to get the data back into a usable flex object.

Lets start working through an example by getting our workspace setup.

 

Initial Setup

Flex and Java both need to know about BlazeDS and where to look for the libraries and configuration files. FlashBuilder lends a hand with this by automating some of the process.

First things first, you’ll need to have FlashBuilder installed. The beta version can be downloaded at http://labs.adobe.com/technologies/flashbuilder4/.  Also check to make sure you have the WTP extensions installed in eclipse so you can automate creating the web application structure.

Finally for this IDE example we’re going to download the BlazeDS war from adobe at: http://opensource.adobe.com/wiki/display/blazeds/Release+Builds Just download the binary version, we don’t need the full turnkey for this. Once you have it downloaded, extract it to your drive, you should see the blazeds.war when you’re done.

In FlashBuilder create a new Flash project. Select J2EE Application server type. Select Remote object access with BlazeDS and the type. Select create combined Java/Flex using WTP. Click next.

 

On the next page, for the BlazeDS WAR file, point to the location where you extracted the files from Adobe. The system will pull all the jar files and configs from this war and add them to your project. Click finish.

You’ll notice that FlashBuilder loaded all the Jars and Config files as well as setting up the web.xml.

The web.xml tells java where to find the config files that BlazeDS needs. Remembering that Flex and Java are compiled separately and both need to know where configuration files are, lets find out where the IDE tells Flex about the config files.

Looking under the project properties under flex compiler you’ll see a compiler option is added for services.

NOTE: Without this compiler option Flex would not be able to find the BlazeDS services. When setting up blazeDS manually this flag will needed to be added by hand.

Java vs Flex: In Java the config files are loaded at run time. To change a value in the property file you simply need to restart the server to make it take effect. In Flex however this is a compile time include which means any changes to the files will need to be rebuilt into the application. Just a little note that may save you some headaches later.

 

That’s is for the setup.

Next time we’ll look at the code needed to use BlazeDS.  Stay tuned.