2 Replies Latest reply on Jul 23, 2012 9:21 AM by Gerald Weber

    core and "topics" without JMS

    Gerald Weber Newbie

      Hi,

       

      i try to implement a simple scenario to send messages between an embedded server and client ( 2 different processes connected via netty transport)

      The system uses core api only, without any JMS stuff, except for the Topic idea.

      I need the message published to all clients listening to this queue.

       

      My Server created a Queue named fsevents, a producer, fetches data from an external source and writes the data to the queue:

      {code}

      sf = serverLocator.createSessionFactory();

      coreSession = sf.createSession(true,true,0);

      coreSession.createQueue(topicName, topicName, true);

      producer = coreSession.createProducer(topicName);

      {/code}

       

      The client connects to the queue and waits for messages matching a specific selector:

       

      {code}

      session.createTemporaryQueue(topicName, clientID);

      messageConsumer = session.createConsumer(topicName,"CCAgent = '"+filter+"'");

      msg = messageConsumer.receive(5000);

      {/code}

       

      queueName = fsevents

      clientID depends on the given commandline parameter

       

      This works as long as i only start 1 client (e,g. clientID client1)

      client1 receives all messages.

       

      When i start another client with clientID client2, the behaviour is the same as a normal queue.

      message1 to client1, message2 to client2

       

      I thought a topic is basically a createTemporaryQueue(address,queuename), so my clients use

      createQueue("fsevents","client1") and createTemporaryQueue("fsevents","client2")  and then set a consumer to listen to the queue.

       

      I'm sure i'm missing something.

      Why does my clients get only every 2nd message ?

       

      thanks,

      gw

        • 1. Re: core and "topics" without JMS
          Jeff Mesnil Master

          You are confusing the semantics of HornetQ core API

           

          Have a look at http://www.slideshare.net/gavinhogan/hornet-q-andthewebjudcon2010-7381151 (esp. starting from slide 53).

           

          basically, using HornetQ core API, you send to an *address* and receives from *queues*

          it's the way you bind queues to address that defines the messaging model

           

           

          coreSession.createQueue(topicName, topicName, true);

           

          => You have created a queue with the name topicName (2nd param) bound to the *address* topicName (1st param)

           

          session.createTemporaryQueue(topicName, clientID);

          => You create a temp queue named clientID bound to the *address* topicName

           

          messageConsumer = session.createConsumer(topicName,"CCAgent = '"+filter+"'");

          => You have create a consumer which will receive message from the *queue* named topicName. That's not what you want.

           

          From your code, the 2 consumers receives messages from the queue named *topicName*, not from the temp queues you have created.

           

          Have a look at the HornetQ javadoc API to avoid confusing address, queues: http://docs.jboss.org/hornetq/2.3.0.Alpha/docs/api/org/hornetq/api/core/client/ClientSession.html

          To fix this:

          1. There is no need to create a queue for the producer, it will send messages to an *address* fsevents

          2. Create temp queues named "client1" & "client2" bound to the "fsevents" address

          3. create consumers for the temp queues "client1" & "client2" and you're all set.

           

          jeff

          • 2. Re: core and "topics" without JMS
            Gerald Weber Newbie

            Thanks Jeff, the slides made it very clear.

            Changes my code and it's working now.

             

            Thanks !