Akka (java), non blocking broadcast to all children

Question

Let's say I have a Region Actor, and each region has a certain number of people inside it. How do you broadcast a message to everyone, knowing that the list of people can change over time, broadcast routers seems to be the choice, but then the problem is that they have a maximum number of routees, and that I cannot dynamically append people to a router.

My question is: I know there is an EventBus, I could subscribe my people to the event Bus, but I dont want them to recieve every message posted, I want them to recieve the messages of the region.

right now in akka, we have to create a router with a certain number of routees, example :

Router router = new router(person1, person2)

this is bad because At the beggining there is no one in the region, i don't know the people who will join my region.

is there a way to make a kind of dynamic router : example :

Region region = new region()
region.router = new Router()
Person person1 = new Person()
region.router.subscribe(person1);     
region.router.tell("hello",null);

Answer 1

Your solution is already very close: you need a router, but not one of the special-made pre-fabricated ones. Instead just write an actor which forwards messages to subscribers:

class MyRouter extends UntypedActor {
  final Set<ActorRef> subscribers = new HashSet<ActorRef>();

  @Override public void onReceive(Object msg) {
    if (msg instanceof Subscribe) {
      subscribers.add(getSender());
    } else if (msg instanceof Unsubscribe) {
      subscribers.remove(getSender());
    } else {
      for (ActorRef target: subscribers) {
        target.tell(msg, getSender());
      }
    }
  }
}