on async topic if I followed we are at the point where we are looking for an activation on the observer side.

Since Java 8 has now CompletableFuture it would be great to use it. Today the spec doesnt use observer returned values so it is mainly a bad practise to have one even if not strictly forbidden - BTW never saw it in real applications - plus spec is not compatible - not specified at all - with CompletableFuture since it is a new API so we can use it as a marker.

This is quite interesting for few reasons:

1- we have our double activation

2- API is user friendly (observer is async and has an async signature)

3- open door for future async enhancements (hopefully not in CDI) with composition of these observers

Only point I'm not sure is should these observers support sync events. I don't see anything blocking to do it but can have missed something.

wdyt?