Does JBossMessaging imposes Message Order?

[mskonda]

Tim/Team

I have a business requirement to preserve the order of messages posted on a topic. AFAIK, JMS doesn't define the message ordering. However, few providers went a mile ahead and implemented message ordering above the spec.

How about JBM? If I use 1.2.0, can I get the Message order by default? I vaguely remember you mentioning on one of the posts that JBM Message order is 'coincidental' (I searched hundreds of your posts but no success to find that). Could you enlighten me on this?

I see that in 1.4.0 you have implemented DefaultMessageOrdering attribute in ServerPeer so the ordering can be preserved (across cluster and not cluster, am I right?). However, we are a bit far away to go with this version yet.

Thanks
Madhu

[timfox]

Madhu-

I'm not sure i understand your question. Can you elaborate / rephrase ?

[mskonda]

Here we go:

My requirement is to fetch the messages from a topic in the same order they have been published. If Messages M1, M2, M3 are published in that order, my consumers should receive them in the same order --> M1, M2 and M3.

Is this possible with JBM 1.2?

[timfox]

No.

That defeats the purpose of using a topic, since you'd have to effectively serialize delivery across all consumers.

If you want that use a queue.

[mskonda]

Tim, could you explain me why this isn't possible for Topic?AFAIK, if there's only one subscriber, the order is preserved. However, why is it different if I have multiple subscribers? Could you give me details technically?

[timfox]

Madhu-

I'm not sure if I understand your question still.

a) Clearly each individually subscriber receives messages in order. Is that what you mean?

b) Or do you mean that each consumer receives the same particular message before receiving the same particular message?

b) would be extremely difficult (and not desirable) to do since it would involve distributed locking.