BlazeDS Uage---RPC service example

BlazeDS Uage---RPC service example

Configure an existing J2EE web application to support BlazeDS by performing the following steps:
1 Add the BlazeDS JAR files and dependent JAR files to the WEB-INF/lib directory.
2 Edit the BlazeDS configuration files in the WEB-INF/flex directory.
3 Define MessageBrokerServlet and a session listener in WEB-INF/web.xml.

RPC service example
The Remoting Service is one of the RPC services included with BlazeDS. The Remoting Service lets clients access methods of Plain Old Java Objects (POJOs) on the server.In this example, you deploy a Java class, EchoService.java, on the server that echoes back a String passed to it from the client. The following code shows the definition of EchoService.java:

1  package  remoting;
2  public   class  EchoService
3  {
4       public  String echo(String text) {
5           return   " Server says: I received ' "   +  text  +   " ' from you " ;
6      }
7  }
8 

The echo() method takes a String argument and returns it with additional text. After compiling EchoService.java,place EchoService.class in the WEB-INF/classes/remoting directory. Notice that the Java class does not have to import or reference any BlazeDS resources.
Define a destination, and reference one or more channels that transport the data. Configure EchoService.class as a remoting destination by editing the WEB-INF/flex/remoting-config.xml file and adding the following code:

< destination  id ="echoServiceDestination"  channels ="my-amf" >
  < properties >
   < source > remoting.EchoService </ source >
  </ properties >
</ destination >

The source element references the Java class, and the channels attribute references a channel called my-amf.Define the my-amf channel in WEB-INF/flex/services-config.xml, as the following example shows:

< channel-definition  id ="my-amf"  class ="mx.messaging.channels.AMFChannel" >
     < endpoint  url ="http://{server.name}:{server.port}/{context.root}/messagebroker/amf"  class ="flex.messaging.endpoints.AMFEndpoint" />
     < properties >
         < polling-enabled > false </ polling-enabled >
     </ properties >
</ channel-definition >

The channel definition specifies that the Flex client uses a non-polling AMFChannel to communicate with the AMFEndpoint on the server.
Note: If you deploy this application on the samples web application installed with BlazeDS, services-config.xml already contains a definition for the my-amf channel.The Flex client application uses the RemoteObject component to access EchoService. The RemoteObject component uses the destination property to specify the destination. The user clicks the Button control to invoke the remote
echo() method:

<? xml version="1.0" ?>
<!--  intro\intro_remoting.mxml  -->
< mx:Application  xmlns:mx ="http://www.adobe.com/2006/mxml"  width ="100%"  height ="100%" >
< mx:Script >
<![CDATA[
 import mx.rpc.events.FaultEvent;
 import mx.rpc.events.ResultEvent;
 // Send the message in response to a Button click.
 private function echo():void {
    var text:String = ti.text;
    remoteObject.echo(text);
 }
 // Handle the recevied message.
 private function resultHandler(event:ResultEvent):void {
     ta.text += "Server responded: "+ event.result + "\n";
 }
 // Handle a message fault.
 private function faultHandler(event:FaultEvent):void {
     ta.text += "Received fault: " + event.fault + "\n";
 }
  ]]>
</ mx:Script >
< mx:RemoteObject  id ="remoteObject"  destination ="echoServiceDestination"  result ="resultHandler(event);"  fault ="faultHandler(event);" />
< mx:Label  text ="Enter a text for the server to echo" />
< mx:TextInput  id ="ti"  text ="Hello World!" />
< mx:Button  label ="Send"  click ="echo();" />
< mx:TextArea  id ="ta"  width ="100%"  height ="100%" />
</ mx:Application >

Compile the client application into a SWF file by using Flex Builder or the mxmlc compiler, and then deploy it to
your web application.