how to push data from BlazeDS without receive message from Flex client?

Question

I am using BlazeDS for data-push feature in my Flex application project. From the official tutorial, Getting started with BlazeDS, it shows messaging example with producer/consumer from API.

but how can I implement server side which doesn't need to be invoke from Flex client, but from within server-side instead. I got some idea but I don't know how to do because I'm a Flex developer, not Java developer, so I think you can help me.

1. In Google, there's a tutorial show about I need to extend ServiceAdapter class in Java-side, which extends Invoke method. Do I need to extend other class instead of this to do what I want?

2. How to configure the message-config.xml to get the result like I describe above?

Answer 1

Here is test code I wrote and use, at times, to test sending data to our client. It's a stripped down, bare bones Java example of a ServiceAdapter implementation. It removes a lot of unnecessary code from the existing examples on the web. It Compiles, works and I use it often in testing.

package your.package.structure.adapter;

import your.package.structure.device.DevicePort;
import flex.messaging.messages.AsyncMessage;
import flex.messaging.messages.Message;
import flex.messaging.services.MessageService;
import flex.messaging.services.ServiceAdapter;
import flex.messaging.util.UUIDUtils;

    /**
     * Test service adapter.  Great for testing when you want to JUST SEND AN OBJECT and nothing
     * else.  This class has to stay in the main codebase (instead of test) because, when it's used
     * it needs to be deployed to Tomcat.
     * @author Kevin G
     *
     */

public class TestServiceAdapter extends ServiceAdapter {

    private volatile boolean running;

    private Message createTestMessage() {
        DevicePort objectToSend = new DevicePort("RouterDevice");

        final AsyncMessage msg = new AsyncMessage();
        msg.setDestination(getClass().getSimpleName() + "Destination");
        msg.setClientId(UUIDUtils.createUUID());
        msg.setMessageId(UUIDUtils.createUUID());
        msg.setBody(objectToSend);

        return msg;
    }

    private void sendMessageToClients(Message msg) {
        ((MessageService) getDestination().getService()).pushMessageToClients(msg, false);
    }

    /**
     * @see flex.messaging.services.ServiceAdapter#start()
     */
    @Override
    public void start(){    
        super.start();

        Thread messageSender = new Thread(){
            public void run(){
                running = true;
                while(running){
                    sendMessageToClients(createTestMessage());
                    secondsToSleep(3);
                }
            }
        };

        messageSender.start();        
    }
    /**
     * @see flex.messaging.services.ServiceAdapter#stop()
     */
    @Override
    public void stop(){
        super.stop();
        running = false;
    }
    /**
     * This method is called when a producer sends a message to the destination. Currently,
     * we don't care when that happens.
     */
    @Override
    public Object invoke(Message message) {
        if (message.getBody().equals("stop")) {
            running = false;
        }
        return null;
    }
    private void secondsToSleep(int seconds) {
        try{
            Thread.sleep(seconds * 1000);
        }catch(InterruptedException e){
            System.out.println("TestServiceAdapter Interrupted while sending messages");
            e.printStackTrace();
        }
    }        
}

You need to set a few properties in tomcat to get this to work.

In messaging-config.xml, you need to add an adapter and destination:

Add this line to the existing <adapters> tag:

 <adapter-definition id="TestServiceAdapter" class="your.package.structure.adapter.TestServiceAdapter"/>

Add this destination to that same messaging-config.xml file:

<destination id="TestServiceAdapterDestination">
        <channels>
            <channel ref="my-streaming-amf"/>
        </channels>
        <adapter ref="TestServiceAdapter"/>
    </destination>

Finally, make sure the "my-streaming-amf" channel is defined in services-config.xml, as in:

<channel-definition id="my-streaming-amf" class="mx.messaging.channels.StreamingAMFChannel">
        <endpoint url="http://{server.name}:{server.port}/{context.root}/messagebroker/streamingamf" class="flex.messaging.endpoints.StreamingAMFEndpoint"/>
        <properties>
             <!-- you don't need to set all these properties, this is just what we set, included for illustration, only -->
            <idle-timeout-minutes>0</idle-timeout-minutes>
            <max-streaming-clients>10</max-streaming-clients>
                <server-to-client-heartbeat-millis>5000</server-to-client-heartbeat-millis>
            <user-agent-settings>
                <user-agent match-on="Safari" kickstart-bytes="2048" max-streaming-connections-per-session="10"/>  
                <user-agent match-on="MSIE" kickstart-bytes="2048" max-streaming-connections-per-session="15"/> 
                <user-agent match-on="Firefox" kickstart-bytes="2048" max-streaming-connections-per-session="10"/>
            </user-agent-settings>
        </properties>
    </channel-definition>

Note that in blazeDS, these two config files (messaging-config.xml and services-config.xml) are located in the following directory:

/blazeds/tomcat/webapps/[nameOfYourApp]/WEB-INF/flex/

where [nameOfYourApp] is the directory your webapp lives in.

I hope all that helps!

-kg