Yes, user code only uses the JMS API. But the client is indirectly using ActiveMQ classes since the JMS interfaces are ActiveMQ implementations. And since the in vm transport does not serialize the ActiveMQ messages it sends to the broker, the broker needs to be in the same classloader as the app. Otherwise, I'm sure the server would throw class cast exceptions.
If you're sending a message from one EAR to another using user objects serialized, thats true. I guess in this case, we should ensure that the tcp protocol is used to ensure data is serialized into and out of each EAR/class loader.
We should reserve the VM transport for use cases where publishers and consumers are in the same class loader - will add warnings to the website to this effect.
James ------- http://radio.weblogs.com/0112098/
