There are several open source JMS implementations extant.
Googling on 'jms "open source"' gives several options in the first
page alone.

Regards,

Patrick

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eh?

What kind of message/event/signal do you need to be transferred?

How does the message need to be transferred?  Object-to-object,
Thread-to-thread, or process-to-process?

If its a simple Object-to-object 'framework', then role your own its
very simple. Or use the Publish/Subscriber classes contained within the JDK.

if its the others, then we'll talk about them too...but give us some
kind of indication as to which 'Can of worms' you want to open.

Andy