A game of ping pong using Akka Actors. For a version that is persisted using Event-Sourcing see this gist: https://gist.github.com/jboner/9990435

GameOfPingPong.scala

package demo

import akka.actor.{Actor, Props, ActorSystem}

object PingPong extends App {
  case object Ball

  class Ping extends Actor {
    var counter = 0

    def receive = {
      case Ball =>
        counter += 1
        println(s"Ping counter: ${counter}")
        Thread.sleep(1000) // you should *never* call Thread.sleep in a real application, just here to slow things down
        sender ! Ball
    }
  }

  class Pong extends Actor {
    var counter = 0

    def receive = {
      case Ball =>
        counter += 1
        println(s"Pong counter: ${counter}")
        Thread.sleep(1000)
        sender ! Ball
    }
  }

  val system = ActorSystem("pingpong")

  val ping = system.actorOf(Props(classOf[Ping]), "ping")
  val pong = system.actorOf(Props(classOf[Pong]), "pong")

  ping.tell(Ball, pong)
}