gistfile1.scala

case class RegisterDispatcher(ref: ActorRef, matcher: String)

class MasterActor extends Actor {
  def receive = {
    case RegisterDispatcher(ref, matcher) => //.. add ref to registry. watch the ref to remove the entry should the actor terminate.
    case s: String => // look in the registry for a match amd dispatch accordingly.
  
  } 
}

class ActorA(master: ActorRef) {
  master ! RegisterDispatcher(self, "bar")
  def receive = {
    //.. Handle message
  }
}
class ActorB(master: ActorRef) {
  master ! RegisterDispatcher(self, "foo")
  def receive = {
    //.. Handle message
  }
}

object Main extends App {
  val sys = ActorSystem("sys")
  val master = sys.actorOf(Props[MasterActor])
  sys.actorOf(Props(new ActorA(master)))
  sys.actorOf(Props(new ActorB(master)))
  
  // Time passes... 
  
  master ! "foo"
  master ! "bar"
}