Asynchronous communication among clients?

[L Chan]

Hi,
I'm relatively new to J2EE...so bear with me if I'm using incorrect terminology...
Anyway, I'd like to know if there's a way (in effect) to communicate among client applications within the J2EE framework. For example, let's say we have three Swing client applications. Each Swing client is associated with a stateful session bean. In turn, all three of these stateful session beans is associated with only one entity bean. A client could call business methods on the stateful session bean which in turn calls a setter method that updates/changes the state of an entity in a persistence store. Or to make the example even easier, forget about the stateful session bean and just envision an example of three Swing clients and one entity bean...
However, I want changes to this entity to be communicated back to the other two Swing clients (e.g. the Swing client updates some information in its window). How can I do this using only J2EE concepts and techniques without resorting to creating sockets, threads, listeners, etc.? Is this even possible in J2EE (I've been told this isn't possible)?

[L Chan]

BTW, I forgot to mention that I'd like a solution that doesn't involve some sort of constant refresh (let's say every second) of the Swing client (i.e. the client uses a getter method to get method information from the session/entity bean). This is probably not very scalable.

[C. Nimo]

Hi.
I suppose your best option is to use JMS for messaging your updates to the clients.
Nimo.

[L Chan]

Originally posted by C. Nimo:
Hi.
I suppose your best option is to use JMS for messaging your updates to the clients.
Nimo.

But I thought that only client beans can subscribe to these updates (as a topic)? However, a Swing client itself cannot subscribe to them. I thought about using this previously - let's assume the session beans can subscribe to the messages - how will it be able to relay this change back to the Swing client without using constant refreshes and stay within the J2EE framework (no writing of threads, sockets, etc.)?

[Roland Barcia]

In stand alone clients, you can use a regualr JMS Listener to recieve asynchronous request. An EJB can write to w JMS queue and send it to a stand alone Java App as long as they share the same queueing system.

[L Chan]

Originally posted by Roland Barcia:
In stand alone clients, you can use a regualr JMS Listener to recieve asynchronous request. An EJB can write to w JMS queue and send it to a stand alone Java App as long as they share the same queueing system.

Thanks for all the help, guys! Yes, a regular JMS listener will work - didn't think about that - but then again, that's why I'm a novice. Thanks!