Akka event bus simple publisher/subscriber code

AkkaEventBusExample.scala

package main

import akka.actor._
import akka.event.{EventBus, SubchannelClassification}
import akka.util.Subclassification

object SCEventBus extends EventBus with SubchannelClassification {
  type Event = (String, Any, ActorRef)
  type Classifier = String
  type Subscriber = ActorRef

  override protected def classify(event: Event): Classifier = event._1

  protected def subclassification = new Subclassification[Classifier] {
    def isEqual(x: Classifier, y: Classifier) = x == y

    def isSubclass(x: Classifier, y: Classifier) = x.startsWith(y)
  }

  override protected def publish(event: Event, subscriber: Subscriber): Unit =
    subscriber.tell(event._2, event._3)
}


class Subscriber extends Actor {

  override def receive: Actor.Receive = {
    case (payload: Any) =>
      println(s"Subscriber: $sender -> $payload")
  }
}

class Publisher extends Actor {

  override def receive: Actor.Receive = {
    case (payload: Any) =>
      println(s"Publisher: $sender -> $payload")
  }
}


object Main extends App {

  val system = ActorSystem()


  // create subscribers
  val rootSubscriber = system.actorOf(Props[Subscriber], "rootSubscriber")

  val eventSubscriber = system.actorOf(Props[Subscriber], "eventSubscriber")

  val itemSubscriber = system.actorOf(Props[Subscriber], "itemSubscriber")

  // set up subscriptions
  SCEventBus.subscribe(rootSubscriber, "/")
  SCEventBus.subscribe(eventSubscriber, "/event")
  SCEventBus.subscribe(itemSubscriber, "/event/42")

  // create event publisher
  val eventPublisher = system.actorOf(Props[Publisher], "eventPublisher")

  // generate some events
  SCEventBus.publish(("/", "payload A", eventPublisher))
  SCEventBus.publish(("/event", "payload B", eventPublisher))
  SCEventBus.publish(("/event/42", "payload C", eventPublisher))
}