[mml]

This is pretty much exactly how AWS SWF handles it.

The java implementation of the workflow "decider" (supervising actor) is somewhat interesting as well. It actually creates a bunch of future/promise objects and replays the workflow from the top as the promises are delivered (which of course has the implication that workflow decider processes must be deterministic!).

I suspect, but don't know, that AMZN has been dogfooding this product in a big way for quite some time.

(full disclosure: just spent some time with the swf guys in seattle)

On the other hand, It seems like the long way around to inventing Erlang ;)