JMS request/ Response Model using MDB.

[Mohammed Yousuff]

I am trying use JMS for request/response model using MDB, i.e when a client sent Message to Server (Here is our MDB). The MDB should send the response back to the same Client which sent the messge.

I found some examples in net which explains the same scnario but both client & server are J2SE.But what I am try is my server should be MDB Bean.
I appriciate if you can throw some lights… please let me know if any example code is avilable.

[Piyush Kr]

[color=darkblue][size=12]Hi, I deployed an MDB a few days ago on weblogic and created a simple java client that produced message and the MDB consumed it.

The code available on the internet is for creating message producers and consumers using JMS API which is not what you want.

Following are the steps which you need to do for what you want -

1. Create an MDB (a born message consumer).
2. Make sure that it implements MessageListener interface in addition to MessageDrivenBean interface.
3. Write your code (for what you want to do with the messsage received by the MDB)
in the onMessage(Message m) method. For example -

    public void onMessage(Message msg) {
		         
		try{
			if(msg instanceof TextMessage){
				
				TextMessage tmsg = (TextMessage)msg;
				PrintWriter out = new PrintWriter("D:\\Test.txt");
				out.println(tmsg.getText());
				out.flush();
				out.close();
			}
		}catch(JMSException ex){
			ex.printStackTrace();
		}
		catch(IOException ioe){
			ioe.printStackTrace();
		}
	}

4. If you want your MDB to talk with the client which sent the message(which is what MDB's are not made for)
you can write JMS producer code also, in the onMessage method.

5. Create a ConnectionFactory and a Queue(or Topic) in your JMS server (provided by J2EE app server).
(In weblogic I created JMS server and a ConnectionFactory and a Queue using admin console)
6. In deployment descriptor add entries for JNDI names of the ConnectionFactory and the Queue.
7. Deploy the bean.
8. Create a message producer client by using the standard JMS api as,

   
package client;

import java.util.Properties;

import javax.jms.Connection;
import javax.jms.ConnectionFactory;
import javax.jms.JMSException;

import javax.jms.MessageProducer;
import javax.jms.Queue;
import javax.jms.Session;
import javax.jms.TextMessage;
import javax.naming.Context;
import javax.naming.InitialContext;
import javax.naming.NamingException;

public class MyMessageSender {

	/**
	 * @param args
	 */
	public static void main(String[] args) {
		try{
			Properties props =new Properties();

			props.put(Context.INITIAL_CONTEXT_FACTORY,"weblogic.jndi.WLInitialContextFactory");
			props.put(Context.PROVIDER_URL,"t3://localhost:7001");
			InitialContext ic = new InitialContext(props);
			ConnectionFactory factory = (javax.jms.ConnectionFactory)ic.lookup("piyush.connectionfactory");
			Connection con = factory.createConnection();
			Session session = con.createSession(false,Session.AUTO_ACKNOWLEDGE);
			Queue queue = (Queue)ic.lookup("piyush.testmessagequeue");
			MessageProducer ms = session.createProducer(queue);
			con.start();
			TextMessage tm = session.createTextMessage("Hello");
			ms.send(tm);	
			System.out.println("Done");
			 	
			
		}catch(NamingException ne){
			ne.printStackTrace();
		}
		catch(JMSException je){
			je.printStackTrace();
		}
		
	}

}

 

9. If you want this client to recieve back the message, create a message consumer also, code is pretty similar to that shown above for creating a message producer.
10. I needed wlclient.jar (in the classpath) since i did it in weblogic. For other servers the jar file and the second argument in the statements,

   props.put(Context.INITIAL_CONTEXT_FACTORY,"weblogic.jndi.WLInitialContextFactory"); 
            props.put(Context.PROVIDER_URL,"t3://localhost:7001"); 

will change.
11. In above code, piyush.connectionfactory and piyush.testmessagequeue are JNDI names of the resources created on the JMS server.

Try doing that. Hope it would help.

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