Communication between actors

Communication.scala

package com.packt.chapter1

import akka.actor.{Actor, ActorRef, ActorSystem, Props}
import scala.util.Random._

/**
  * Which contains messages to be sent to the actors.
  * Actors will use these messages for communication.
  */
object Messages {
  case class Done(randomNumber: Int)
  case object GiveMeRandomNumber
  case class Start(actorRef: ActorRef)
}

/**
  * Receives the message `GiveMeRandomNumber`
  */
class RandomNumberGeneratorActor extends Actor {
  import Messages._
  override def receive: Receive = {
    case GiveMeRandomNumber =>
      println("received a message to generate a random integer")
      val randomNumber = nextInt
      sender ! Done(randomNumber)
  }

}

/**
  * sends the message to `RandomNumberGenerator`,
  * and receives the result in case of `Done`.
  */
class QueryActor extends Actor {
  import Messages._
  override def receive: Receive = {
    case Start(actorRef) => println(s"send me the next random number")
      actorRef ! GiveMeRandomNumber
    case Done(randomNumber) =>
      println(s"received a random number $randomNumber")
  }
}

object Communication extends App {
  import Messages._
  val actorSystem = ActorSystem("HelloAkka")
  val randomNumberGenerator = actorSystem.actorOf(Props[RandomNumberGeneratorActor], "randomNumberGeneratorActor")
  val queryActor = actorSystem.actorOf(Props[QueryActor], "queryActor")
  queryActor ! Start(randomNumberGenerator)
}