Example of Akka's EventBus

EventBusTest.scala

import akka.actor._
import akka.event._

object EventBusTest extends App {

  // message
  trait EventMessage
  case class PublishEventMessage() extends EventMessage

  // event bus
  class LookupBusImpl extends EventBus with LookupClassification {
    type Event = EventMessage
    type Classifier = String
    type Subscriber = ActorRef

    override protected def mapSize(): Int = 128

    override protected def publish(event: Event, subscriber: Subscriber): Unit = {
      subscriber ! event
    }

    override protected def classify(event: Event): Classifier = "crawler-event-bus"

    override protected def compareSubscribers(a: Subscriber, b: Subscriber): Int = a.compareTo(b)
  }

  // subscriber
  class SampleActor extends Actor {
    def receive = {
      case m: PublishEventMessage => println("** publish **")
    }
  }

  // initialize
  val actorSystem = ActorSystem("system")
  val actor1 = actorSystem.actorOf(Props[SampleActor])
  val actor2 = actorSystem.actorOf(Props[SampleActor])

  val lookupBus = new LookupBusImpl()

  // subscribe
  lookupBus.subscribe(actor1, "crawler-event-bus")
  lookupBus.subscribe(actor2, "crawler-event-bus")

  // publish
  lookupBus.publish(PublishEventMessage())
  
}