7 Replies Latest reply on Jun 2, 2011 1:25 PM by Clebert Suconic

    Configuring message consumption

    Abbas Raza Newbie

      Hello,

       

      I am evaluating HornetQ for asynchronous messaging use cases that I have. The two types of use cases that I have are the regular ones.

       

      1. Message producers and consumers exchange messages asynchronously without JMS.

      2. Migrate existing MDBs to use the core HornetQ APIs.

       

      In both of these cases, I prefer to keep the message consumption configurable. By that, I mean some configuration for client consumer similar to the way MDBs are configured in containers. The container manages the life cycle of the MDB. From HornetQ documentation, examples, and user forum posts, I do not see any way of doing that. From what I see, we have to keep the session pipe open for a client consumer, which in turn calls the MessageHandler upon receipt of message. Is client consumer configuration in the works? Or that is not the right way to do it? Any help appreciated.

       

      Thanks!

        • 1. Re: Configuring message consumption
          Clebert Suconic Master

          1. You can easily do something with the micro container.

           

          If you have suggestions... I'm all ears to anything.

           

          Anything that would help kill MDBs ;-)

           

          - The core-API is a low-level API, independent of the application server. You need a ClientConsumer for each "handler" you want to have. (That's actually how we do on the Resource Adapter.. we have a few sessions configured).

           

          - if you batch transactions, you will not need to have multiple threads.

           

           

          2. MDBs are using the Transaction Manager. Are you planning using the Transaction Manager also (XA)?

           

           

           

           

          Take a look also on the Asynchronous Send Example. That may

          • 2. Re: Configuring message consumption
            Abbas Raza Newbie

            Yes, I do want MDBs to go away. Primarily I am looking at a way to configure a client consumer in say hornetq-configuration.xml or hornetq-beans.xml. HornetQ can, at runtime, instantiate and invoke the client consumer and pass on the messages received. This would obviate us to programmatically keep the session active and run client consumers for the x number of topics we have. Does it seem practical? Thanks!

            • 3. Re: Configuring message consumption
              Abbas Raza Newbie

              I tried some use cases myself based on the docs and examples. I couldn't find an asynchronous send example. Regardless, it seems counter intuititve for me to start a consumer myself for receiving messages. From an asynchronous perspective, the messaging platform would allow registering of listeners and dispatch messages to the listeners that they are interested in. With HornetQ, I have to start the consumers myself and wait for messages. As I mentioned my earlier post, I expected that we can register the message listeners/handlers in some xml file. These listeners are to be  instantiated by the messaging platform for dispatching messages. Please let me know if I am missing something. Thanks!

              • 4. Re: Configuring message consumption
                Clebert Suconic Master

                You could do something like this:

                 

                 

                class MyBean implements MessageHandler

                {

                     ClientSession session; //

                     ClientConsumer consumer;//

                    public void start()

                    {

                         ClientSession...  // do the whole initialization here

                          ClientConsumer ... // initialize the consumer

                          session.start();

                 

                         consumer.setMessageHandler(this);

                 

                        // make sure you have these things with a reference being held.

                 

                 

                    }

                 

                   public void stop()

                    {

                         // close your session and consumers here

                    }

                 

                 

                }

                 

                 

                And add that class into hornetq-beans.xml (with a dependency to the server).

                 

                 

                Whatever you do, it will go through these steps. (even if you used something that would do it automagically for you)

                 

                 

                If we added something that would register a listener for you, this is what would happen under the covers.

                • 5. Re: Configuring message consumption
                  Clebert Suconic Master

                  If you are interested... the Spring integration that Bill Burke wrote has something as well. You should take a look.

                   

                   

                  BTW: The example I was referring was send-acknowledgements.

                  • 6. Re: Configuring message consumption
                    Abbas Raza Newbie

                    Ah. That would help. Couple of questions.

                     

                    1. Is there an XSD for hornetq--beans.xml? I did not find one in the schemas directory. It would help in figuring out the structure.

                    2. Since the message handler would be injected in the server, there would be only one instance of the handler. Having a pool of message handlers would be helpful for scaling. Is it being considered?

                     

                    Thanks for the help! Very positive experience with HornetQ so far. Great job!

                    • 7. Re: Configuring message consumption
                      Clebert Suconic Master

                      People usually will need multiple instances of the consumer (like on MDBs) because MDB will *force* you to commit your message through XA on every received message.

                       

                      I was expecting you would be dealing with transactions yourself and not requiring multiple instances.

                       

                      If you need multiple instances.. I would just open multiple sessions at your instance.  Controlling arrays.. etc.

                       

                       

                      As for the XSD for hornetq-beans... that comes straight from JBoss Micro Container. I'm not sure where's the XSD for that.

                       

                      (BTW: If you are inside JBoss, you could have your own myapp-beans.xml, and the microcontainer would deploy it for you.)