BlazeDS for Java-Flex communication

BlazeDS is a server-based Java remoting and web messaging technology that enables communication between back-end Java applications and Adobe Flex applications running in the browser. In this post, I describe a way (may not be the best) I was able to successfully to build a simple application using BlazeDS and Flex. The application is build using eclipse and ant, rather than using FlexBuilder. Following are the main steps that you have to follow to implement the example.

1. Install tomcat
2. Install Flex sdk
3. Download BlazeDS web application.
4. Create tomcat user with manager permisison
5. Create dynamic web project in eclipse
6. Create java file
7. Create mxml file
8. Update the config files in the WEB-INF/flex directory of the web application
9. Copy flexTasks.tasks to the root directory.
10. Create build file
11. Copy catalina-ant.jar and flextasks.jar into ant lib directory, add them to ant runtime in eclipse.
12. Build application using ant

Skip to Sample Code: Moving the mouse over the bolded code parts shows additional information

1. Install tomcat: This example was implemented on Tomcat 6.0.16
2. Install Flex sdk: You can download the flex sdk from here The example was implemented on Flex 3.0.0
3. Download BlazeDS:Download the BlazeDS web application from here
4. Create tomcat user with manager permisison: In the TOMCAT_HOME/tomcat-users.xml, add the following line

   <role rolename="manager"/>
   <user username="abhi" password="abhi" roles="manager"/>

5. Create dynamic web project in eclipse by importing the BlazeDS Web application war file.
6. Create java fileThe java class simply echoes the data input in the textbox shown in the browser.

   package hello;
   public class HelloWorld {
    
    public String sayHelloTo(String str) {
     System.out.println("Hello " + str);
     return "Hello " + str;
    }
   }

7. Create mxml fileThe mxml file simply shows a text box and a submit button. A label will be displayed below the textbox with the word "Hello" appended to the input text.

   <?xml version="1.0" encoding="utf-8"?> 
   <mx:Application xmlns:mx="http://www.adobe.com/2006/mxml" viewSourceURL="srcview/index.html">
    <mx:Script>
     <![CDATA[
   
      import mx.rpc.events.FaultEvent;
      import mx.rpc.events.ResultEvent;
      
   
      [Bindable]
      private var helloResult:String;
      private function sayHelloTo():void {
       ro.sayHelloTo(inputText.text);
      }
       private function resultHandler(event:ResultEvent):void
      {
       
       helloResult = event.result as String;
      }
   
     ]]>
    </mx:Script> 
        <mx:RemoteObject id="ro" destination="helloworld" result="resultHandler(event)" /> 
        <mx:HBox width="100%">
             <mx:TextInput id="inputText"/>
             <mx:Button label="Submit" click="sayHelloTo()"/>
        </mx:HBox>
        <mx:Label text="{helloResult}"/> 
   </mx:Application>

   Note: Defining the remote object enables you to make calls to the remote Java classes as if they are local action script classes.
8. Update the configuration files For this example, you only have to update one config file, WEB-INF/flex/remoting-config.xml, to add a new destination, the HelloWorld class.

   <?xml version="1.0" encoding="UTF-8"?>
   <service id="remoting-service"
       class="flex.messaging.services.RemotingService">
   
       <adapters>
           <adapter-definition id="java-object" class="flex.messaging.services.remoting.adapters.JavaAdapter" default="true"/>
       </adapters>
   
       <default-channels>
           <channel ref="my-amf"/>
       </default-channels>
       
       <destination id="helloworld">
        <properties>
         <source>hello.HelloWorld</source>
        </properties>
       </destination>
   
       
     </service>
   

9. Copy flexTasks.tasks to the root directory.
10. Create build fileThe ant build file uses two flex specific tasks, mxmlc to compile the mxml file and html-wrapper to create a html wrapper that contains the created swf file.

    <project name="helloWorldServer" default="build" basedir=".">
    
     <!-- ===================== Property Definitions =========================== -->
    
     <property file="build.properties" />
     <property file="${user.home}/build.properties" />
    
    
     <!-- ==================== File and Directory Names ======================== -->
    
     <property name="app.name" value="helloWorldServer" />
     <property name="app.path" value="/${app.name}" />
     <property name="app.version" value="0.1-dev" />
     <property name="build.home" value="${basedir}/build" />
     <property name="catalina.home" value="C:/unzipped/apache-tomcat-6.0.16" />
     <property name="dist.home" value="${basedir}/dist" />
     <property name="docs.home" value="${basedir}/docs" />
     <property name="manager.url" value="http://localhost:8080/manager" />
     <property name="src.home" value="${basedir}/src" />
     <property name="web.home" value="${basedir}/WebContent" />
     <property name="manager.username" value="abhi" />
     <property name="manager.password" value="abhi" />
     <property name="FLEX_HOME" value="C:/Adobe/Flex" />
     <property name="APP_ROOT" value="${basedir}/WebContent" />
    
    
     <!-- ==================== External Dependencies =========================== -->
    
     <!-- ==================== Compilation Classpath =========================== -->
    
     <path id="compile.classpath">
      <fileset dir="${catalina.home}/bin">
       <include name="*.jar" />
      </fileset>
      <pathelement location="${catalina.home}/lib" />
      <fileset dir="${catalina.home}/lib">
       <include name="*.jar" />
      </fileset>
    
     </path>
    
     <!-- ================== Custom Ant Task Definitions ======================= -->
    
    
     <taskdef resource="org/apache/catalina/ant/catalina.tasks" classpathref="compile.classpath" />
     <taskdef resource="flexTasks.tasks" classpath="c:/ant/lib/flexTasks.jar" />
    
     <!--  ==================== Compilation Control Options ==================== -->
    
     <property name="compile.debug" value="true" />
     <property name="compile.deprecation" value="false" />
     <property name="compile.optimize" value="true" />
    
    
    
     <!-- ==================== All Target ====================================== -->
    
     <target name="all" depends="clean,build" description="Clean build and dist directories, then compile" />
    
    
    
     <!-- ==================== Clean Target ==================================== -->
    
     <target name="clean" description="Delete old build and dist directories">
      <delete dir="${build.home}" />
      <delete dir="${dist.home}" />
     </target>
    
    
    
     <!-- ==================== Compile Target ================================== -->
    
     <target name="build" depends="prepare" description="Compile Java sources">
    
      <!-- Compile Java classes as necessary -->
      <mkdir dir="${build.home}/WEB-INF/classes" />
      <javac srcdir="${src.home}" destdir="${build.home}/WEB-INF/classes" debug="${compile.debug}" deprecation="${compile.deprecation}" optimize="${compile.optimize}">
       <classpath refid="compile.classpath" />
      </javac>
    
      <!-- Copy application resources -->
      <copy todir="${build.home}/WEB-INF/classes">
       <fileset dir="${src.home}" excludes="**/*.java" />
      </copy>
    
     </target>
    
    
    
     <!-- ==================== Dist Target ===================================== -->
    
     <target name="dist" depends="build,javadoc" description="Create binary distribution">
    
      <!-- Copy documentation subdirectories -->
      <mkdir dir="${dist.home}/docs" />
      <copy todir="${dist.home}/docs">
       <fileset dir="${docs.home}" />
      </copy>
    
      <!-- Create application JAR file -->
      <jar jarfile="${dist.home}/${app.name}-${app.version}.war" basedir="${build.home}" />
    
      <!-- Copy additional files to ${dist.home} as necessary -->
    
     </target>
    
     <!-- ==================== Flex targets ==================================== -->
    
     <target name="appcompile" depends="install">
      <mxmlc file="${APP_ROOT}/helloWorld.mxml" context-root="/helloWorldServer" keep-generated-actionscript="true" services="${web.home}/WEB-INF/flex/services-config.xml" output="${catalina.home}/webapps/${app.name}/helloWorld.swf">
       <compiler.library-path dir="${FLEX_HOME}/frameworks" append="true">
        <include name="${web.home}/WEB-INF/lib/" />
       </compiler.library-path>
       <load-config filename="${FLEX_HOME}/frameworks/flex-config.xml" />
       <source-path path-element="${FLEX_HOME}/frameworks" />
      </mxmlc>
    
     </target>
    
     <target name="createHtmlWrapper" depends="appcompile">
      <html-wrapper application="${APP_ROOT}/helloWorld.mxml" output="${catalina.home}/webapps/${app.name}" swf="helloWorld" />
     </target>
     
    
     <!-- ==================== Install Target ================================== -->
    
     <target name="install" depends="build" description="Install application to servlet container">
    
      <deploy url="${manager.url}" username="${manager.username}" password="${manager.password}" path="${app.path}" localWar="file://${build.home}" />
    
     </target>
    
    
     <!-- ==================== Javadoc Target ================================== -->
    
     <target name="javadoc" depends="build" description="Create Javadoc API documentation">
    
      <mkdir dir="${dist.home}/docs/api" />
      <javadoc sourcepath="${src.home}" destdir="${dist.home}/docs/api" packagenames="*">
       <classpath refid="compile.classpath" />
      </javadoc>
    
     </target>
    
    
    
     <!-- ====================== List Target =================================== -->
    
     <target name="list" description="List installed applications on servlet container">
    
      <list url="${manager.url}" username="${manager.username}" password="${manager.password}" />
    
     </target>
    
    
     <!-- ==================== Prepare Target ================================== -->
    
     <target name="prepare">
    
      <!-- Create build directories as needed -->
      <mkdir dir="${build.home}" />
      <mkdir dir="${build.home}/WEB-INF" />
      <mkdir dir="${build.home}/WEB-INF/classes" />
    
    
      <!-- Copy static content of this web application -->
      <copy todir="${build.home}">
       <fileset dir="${web.home}" />
      </copy>
    
      <!-- Copy external dependencies as required -->
      <mkdir dir="${build.home}/WEB-INF/lib" />
    
      <!-- Copy static files from external dependencies as needed -->
      <!-- *** CUSTOMIZE HERE AS REQUIRED BY YOUR APPLICATION *** -->
    
     </target>
    
    
     <!-- ==================== Reload Target =================================== -->
    
     <target name="reload" depends="build" description="Reload application on servlet container">
    
      <reload url="${manager.url}" username="${manager.username}" password="${manager.password}" path="${app.path}" />
    
     </target>
    
    
     <!-- ==================== Remove Target =================================== -->
    
     <target name="remove" description="Remove application on servlet container">
    
      <undeploy url="${manager.url}" username="${manager.username}" password="${manager.password}" path="${app.path}" />
    
     </target>
    </project>

11. Addtional ant configuration: Copy catalina-ant.jar and flextasks.jar into ant lib directory, add them to ant runtime in eclipse.
12. To build and install the file, simply run the createHtmlWrapper target in ant

References

• The ant build file was created using the base build.xml file available on apache tomcat website.
• The config files are used as is available with the BlazeDS service.

Weblogic Split Directory Environment

The WebLogic split development directory environment consists of a directory layout and associated Ant tasks that help you repeatedly build, change, and deploy J2EE applications. Using the split directory structure speeds-up the deployment time by avoiding unnecessary copying of files. In the split directory structure, the application directories are split into source and build directories.

• The source directory contains the Java source files, deployment descriptors, JSPs etc. along with static content.
• The build directory contains files generated during the build process.

The source directory is organized as follows:

root (represents the ear)
|_ EJB Modules/web modules
|_ Application Deployment descriptor (application.xml)
|_ Shared utility classes
|_ Common libraries shared by the different modules.

The split development directory structure requires each project to be staged as a J2EE Enterprise Application. BEA recommends that you stage even stand-alone Web applications and EJBs as modules of an Enterprise application, to benefit from the split directory Ant tasks.

Deploying from a Split Development Directory
All WebLogic Server deployment tools (weblogic.Deployer, wldeploy, and the Admin Console) support direct deployment from a split development directory. When an application is deployed to WebLogic Server, the server attempts to use all classes and resources available in the source directory for deploying the application. The server looks in the build directory only for the resources not available in the source directory.

Ant Tasks
The following is a list of Ant tasks that help you deploy applications using the split development directory environment.

• wlcompile—This Ant task compiles the contents of the source directory into subdirectories of the build directory.
• wlappc—Used to generate JSPs and container-specific EJB classes for deployment.
• wldeploy—Deploys any format of J2EE applications (exploded or archived) to WebLogic Server. To deploy directly from the split development directory environment, you specify the build directory of your application.
• wlpackage—Used to generate an EAR file or exploded EAR directory from the source and build directories.

After you set up your source directory structure, use the weblogic.BuildXMLGen utility to create a basic build.xml file. The syntax for weblogic.BuildXMLGen is as follows:

java weblogic.BuildXMLGen [options] 

After running weblogic.BuildXMLGen, edit the generated build.xml file to specify properties for your development environment.

Summary
The following steps illustrate how you use the split development directory structure to build and deploy a WebLogic Server application.

1. Create the main EAR source directory for your project. When using the split development directory environment, you must develop Web Applications and EJBs as part of an Enterprise Application, even if you do not intend to develop multiple J2EE modules.
2. Add one or more subdirectories to the EAR directory for storing the source for Web Applications, EJB components, or shared utility classes.
3. Store all of your editable files (source code, static content, editable deployment descriptors) for modules in subdirectories of the EAR directory.
4. Set your WebLogic Server environment by executing either the setWLSEnv.cmd (Windows) or setWLSEnv.sh (UNIX) script. The scripts are located in the WL_HOME\server\bin\ directory, where WL_HOME is the top-level directory in which WebLogic Server is installed.
5. Use the weblogic.BuildXMLGen utility to generate a default build.xml file for use with your project. Edit the default property values as needed for your environment.
6. Use the default targets in the build.xml file to build, deploy, and package your application.