Topics with AS7 and HornetQ

[lauradp]

Hello everybody!

I'm trying to develop a simple application with a publisher and a subscriber.

To publish a message I wrote che following instructions:

Properties env = new Properties();

env.put(Context.INITIAL_CONTEXT_FACTORY, INITIAL_CONTEXT_FACTORY);

env.put(Context.PROVIDER_URL, PROVIDER_URL);

env.put(Context.SECURITY_PRINCIPAL, DEFAULT_USERNAME);

env.put(Context.SECURITY_CREDENTIALS, DEFAULT_PASSWORD);

env.put("jboss.naming.client.ejb.context", true);

Context ctx = new InitialContext(env);

tconFactory = (TopicConnectionFactory) PortableRemoteObject.narrow(ctx.lookup("jms/RemoteConnectionFactory"),TopicConnectionFactory.class);

tcon = tconFactory.createTopicConnection(DEFAULT_USERNAME,DEFAULT_PASSWORD);

tsession = tcon.createTopicSession(false, Session.AUTO_ACKNOWLEDGE);

topic = (Topic) PortableRemoteObject.narrow(ctx.lookup("jms/"+topicName), Topic.class);

tpublisher = tsession.createPublisher(topic);

msg = tsession.createTextMessage();

tcon.start();

System.out.println("Topic Sender");

System.out.println("Following Messages has been sent !!!");

System.out.println("====================================");

for(int j=1;j<=3;j++){

                    msg.setText(""+j);                     // Messages

                    tpublisher.publish(msg);           // Messages sent

          System.out.println("Message Sent = "+j);

}

System.out.println("====================================");

When I run these instructions I get no error but I cannot see any message from JBoss  Administration Console. Is there any error?

[jmesnil]

do you have a subscriber listening on the topic?

If there are no consumer connected (or durable subscribers), HornetQ will discard the messages sent to the topic (since nobody is interested by them).

[jbertram]

Your code looks fine as far as I can tell.  Although you should try to use ConnectionFactory, Session, Destination, and MessageProducer rather than TopicConnectionFactory, TopicSession, Topic, and TopicPublisher respectively since that is the recommendation from the JMS spec.

Jeff is right.  This is basic JMS semantics with topics.

Try using a queue rather than a topic.

[clebert.suconic]

TopicConnection and QueueConnection are obsolete interfaces. try to use the unified ones.

[lauradp]

Thanks for your answers!

I was trying to develop an example about queues and one about topics in HORNETQ.That's why I used topics instead of queues.

What's is the unified interface??

Thanks

Laura

[jbertram]

Using a topic is fine as long as you understand the basic semantics (i.e. if there are no subscriptions any message sent to the topic will be discarded).

The "unified" interfaces are the ones I referred to in my previous comment.  To be clear, these are unified:

• ConnectionFactory
• Session
• Destination
• MessageProducer

These are not unified:

• QueueConnectionFactory, TopicConnectionFactory
• QueueSession, TopicSession
• Queue, Topic
• QueueSender, TopicPublisher

[lauradp]

Thank you Justin,

so you are suggesting me to always use the unified interfaces and to let "ebj-jar.xml" file to specify the destination type. Isn't it?

thanks

Laura

[jbertram]

I am suggesting that you use the unified interfaces, but I'm not sure where ejb-jar.xml enters your use-case.  You haven't mentioned it until now.  It shouldn't be related at all to how messages are produced.  In terms of messaging, It only controls the behavior of an MDBs consumption of a message.

[lauradp]

ok, thanks

Laura