2 Replies Latest reply on Mar 15, 2005 3:05 AM by mlipp

    Don't get it sorted out: JMS Topic MDB & cluster

      Sorry. I have read through the docs, several postings and the FAQ but I don't get it. Does JBoss 3.2.7 and/or JBoss 4.0.1 support MDBs that are configured as listeners of a durable subscription or does it not (apart from this obviously not being an easy thing to configure)? "Support" means that each message posted to the topic is delivered to exactly one MDB instance in the cluster (I think this is as it should be -- the same as with an MDB listening on a queue).

      I understand that this is more difficult to implement than the case where an MDB listens to a queue, because you get the "deliver once in the cluster" simply because the standard behaviour for a queue is to deliver the message only to one of the listeners, while in the case of a topic messages are delivered to all listeners. So you cannot simply bind to the topic on every node, you either have to bind on only one node (with some fail-over mechanism) or do some additional synchronization among the nodes.

      I have to make a design decision that depends on this information and would be grateful for any hint.

      Thanks

      Michael

        • 1. Re: Don't get it sorted out: JMS Topic MDB & cluster

          1) It is an FAQ and you haven't looked hard enough

          2) It is a question about clustered ejb deployment so you are in the wrong forum
          clustering => clustering forum

          3) I added it to the JMS FAQ about MDB singleton

          4) Eventually the JMS FAQ is just going to be bigger as big as this forum :-(

          • 2. Re: Don't get it sorted out: JMS Topic MDB & cluster

            Thanks. I didn't make the connection between my question and "MDB singleton" because in my scenario, there may be as many MDB instances as appropriate. Several messages may be processed in parallel, even on different nodes, as long as every message is only processed once.

            Concerning (4): Why not put the information in the documentation instead, e.g. 5.5 "Message driven beans in cluster configurations"

            - Michael