Point-to-Point Mode

In this mode, a message is delivered to one destination actor with matching path in the cluster using DistributedPubSubMediator. If there are several entries with matching path, message will be delivered using the specified routing logic.

Registration

You will have to first register with the local mediator actor by sending DistributedPubSubMediator.Put message.

class Destination extends Actor with ActorLogging {
  import DistributedPubSubMediator.Put
  val mediator = DistributedPubSub(context.system).mediator
  // register to the path
  mediator ! Put(self)

  def receive = {
    case s: String ⇒
      log.info("Got {}", s)
  }
}

The actorRef passed to Put (self) in this case, must belong to the same actor system as the mediator actor.

Send

Messages can be sent to destination actors using DistributedPubSubMediator.Sendmessage to the local mediator. You need to specifiy the path of the destination actor (without the address information).

class Sender extends Actor {
  import DistributedPubSubMediator.Send
  // activate the extension
  val mediator = DistributedPubSub(context.system).mediator

  def receive = {
    case in: String ⇒
      val out = in.toUpperCase
      mediator ! Send(path = "/user/destination", msg = out, localAffinity = true)
  }
}

localAffinity = true means if there is a matching actor in the local actor system, then it is preferred over remote actors.

Remove

Actors are automatically removed from the registry when they are terminated, or you can explicitly remove entries with DistributedPubSubMediator.Remove.

SendToAll

It is possible to broadcast a message to all matching actors using DistributedPubSubMediator.SendToAll message.