The question is - how can we provide a point-to-multipoint request-reply mechanism.

I guess the easy answer is JBREM-48 - just have a JGroups transport. I think that there could be a couple more types of session:

* point-to-point - single connection; request-respone (definitely reliable) and oneway (probably reliable) allowed
* point-to-multipoint - oneway only, possibly unreliable (simple protocols like UDP+Multicast or UDP+Broadcast)
* point-to-group - something like JGroups, where you allow request-response with some kind of response aggregation (like a Map of node-IDs to Reply messages [guess this means that Remoting needs to have a concept of an endpoint identifier - and no, I do no think that it should be the connection URI because there won't be a 1:1 correspondance there])

We should provide an SPI thing for all these types, but I don't think it's worth the effort to reinvent what JGroups already has, so the last should be confined to a JGroups transport unless someone contributes something awesome.