Sounds reasonable. I am sure there are a variety of UDP based communication frameworks that can probably be used a starting point and then put in a JCA wrapper, or you could just build from the ground up.
If there is a better (simpler) alternative then I'd really like to hear about it.
Note, don't immediately think of JCA as complex or hard in and of itself. Some of the communication patterns you see on projects like this (ie UDP, SNMP etc) will be addressed in the JCA 2.0 spec. For now, I'd say you have a pretty solid plan.
Having written the UDP RA, is it possible to get any loadbalancing out of running it in a JBoss cluster?
After reading http://www.jboss.com/index.html?module=bb&op=viewtopic&t=86104 it looks like not, but I'd like to double check.
In my case the RAs don't need to share any data, they are 100% independent. All I need is for the load balancer to distribute the incoming UDP packets (unicast, not broadcast as I stated before) in a round-robin fashion, amongst the all the nodes. No 'sticky-session'-like behaviour required at all.