MDB working as a singleton vs MBean

[siocnarf]

Hi all,

I'm quite new to EJB's world and need an advise.

I know that J2EE architecture is not thought to be able to manage singletons but in my current project, I will definitly have to cope with it.

Somewhere in my stuff, I'll need a bean working as a sequencer e.g. something receiving messages and able to forward them in the right order.

what should I do ?

1° write an MDB, limit pool size to 1 and make sure to manage its persistence (by using NonSerializableFactory or DB storage for instance)
2° write an MBean listening to the queues and in that case, will I be sure that only ONE instance of my MBean will be running in the same time ?
3° as JMS destinations are still accessible outside of the server VM, should I use a standalone CORBA server just for the sorting stuff ?

Would someone be kind enough to remind me the assets of using MBeans apart from their being manageable ?


Many thanks for your help.

[pra]

Hi, I have to admit that I am not shure what you are after, but I know this much:

1. An MDB with a pool size set to one, and listening on a queue should receive its messages in the order they where sent.

2. To create a singleton you could use a singleton deployment descriptor for a session bean, to get only one active instance (JBoss specific - look into the manual).

//Peter

[siocnarf]

Hi Peter,

Thanks for your answer.

Actually, my question was only about the different means to create singleton beans. :-)

I think I'd probably write the MDB.