Monitoring support

[rogeralsing]

I know that you are looking into monitoring support on the JVM side.
If I can make a wish, I'd like to see an interface that has an API similair to this:

interface IActorMonitor
{
        void PostRestart(ActorRef actor, ....);
        void PostStop(ActorRef actor, ....)
        ....
}

In most cases, monitoring will probably not be interested in individual actors, it just needs an IncrementStopped() kind of API.

But with a monitoring API like the one proposed above.
We can provide other features, related to monitoring.
e.g. debug visualizers that update in realtime when topology changes.

For example, I did a spike on this, visualizing our chat example:

I think that could be extremely valuable to end users to see how their system or a subsection of the system behaves.
And by allowing the monitoring support to reason about the actual actorref that has been affected, this is pretty easy to accomplish.

[rkuhn]

@rogeralsing, it will probably take a while in ostrich mode until we can meaningfully comment on this suggestion: we are currently looking into how monitoring could potentially be implemented, there are several proposals floating around and we are far from picking a clear winner.