Akka 2.2.3 and 2.1.x remoting difference.

Akka-2.1.4.scala

import akka.actor.{Props, ActorRef, Actor, ActorSystem}
import com.typesafe.config.ConfigFactory
import scala.util.Random
import scala.collection.mutable.LinkedList
import scala.reflect.ClassTag
import scala.collection.mutable
import akka.remote.RemoteActorRefProvider

case class SubscribeReceiver(receiverActor: ActorRef)

case class UnsubscribeReceiver(receiverActor: ActorRef)

object Receiver {
  def main(args: Array[String]) {

    val a = ActorSystem("a", ConfigFactory.parseString(
      """
        |akka.daemonic = on
        |akka.actor.provider = "akka.remote.RemoteActorRefProvider"
        |akka.remote.netty.hostname = "127.0.0.1"
        |akka.remote.transport = "akka.remote.netty.NettyRemoteTransport"
        |akka.remote.netty.connection-timeout = 600s
        |akka.remote.netty.port = 9998
      """.stripMargin))

    val feeder = a.actorOf(Props(new ReceiverActor("akka://[email protected]:9999/user/FeederActor")), "ReceiverActor")

    println("Receiver started as:" + feeder)

    a.awaitTermination()
  }
}

class ReceiverActor[T: ClassTag](urlOfPublisher: String)
  extends Actor {

  lazy private val remotePublisher = context.actorFor(urlOfPublisher)

  override def preStart() = remotePublisher ! SubscribeReceiver(context.self)

  def receive = {
    case msg ⇒ println(msg)
  }

  override def postStop() = remotePublisher ! UnsubscribeReceiver(context.self)

}

class FeederActor extends Actor {

  val rand = new Random()
  var receivers: mutable.LinkedList[ActorRef] = new mutable.LinkedList[ActorRef]()

  val strings: Array[String] = Array("words ", "may ", "count ")
  var i =0
  def makeMessage(): String = {
    i+=1
    val x = rand.nextInt(3)
    strings(x) + strings(2 - x) + i
  }

  /*
   * A thread to generate random messages
   */
  new Thread() {
    override def run() {
      while (true) {
        Thread.sleep(500)
        receivers.foreach(_ ! makeMessage)
      }
    }
  }.start()

  def receive: Receive = {

    case SubscribeReceiver(receiverActor: ActorRef) =>
      println("received subscribe from %s".format(receiverActor.toString))
      receivers = mutable.LinkedList(receiverActor) ++ receivers

    case UnsubscribeReceiver(receiverActor: ActorRef) =>
      println("received unsubscribe from %s".format(receiverActor.toString))
      receivers = receivers.dropWhile(x => x eq receiverActor)

  }
}

object Sender {
  def main(args: Array[String]) {

    val a = ActorSystem("a", ConfigFactory.parseString(
      """
        |akka.daemonic = on
        |akka.actor.provider = "akka.remote.RemoteActorRefProvider"
        |akka.remote.netty.hostname = "127.0.0.1"
        |akka.remote.transport = "akka.remote.netty.NettyRemoteTransport"
        |akka.remote.netty.connection-timeout = 600s
        |akka.remote.netty.port = 9999
      """.stripMargin))

    val feeder = a.actorOf(Props[FeederActor], "FeederActor")

    println("Feeder started as:" + feeder)

    a.awaitTermination()
  }
}

Akka-2.2.3.scala

import akka.actor.{Props, ActorRef, Actor, ActorSystem}
import com.typesafe.config.ConfigFactory
import scala.util.Random
import scala.collection.mutable.LinkedList
import scala.reflect.ClassTag
import scala.collection.mutable

case class SubscribeReceiver(receiverActor: ActorRef)

case class UnsubscribeReceiver(receiverActor: ActorRef)

object Receiver {
  def main(args: Array[String]) {

    val a = ActorSystem("a", ConfigFactory.parseString(
      """
        |akka.daemonic = on
        |akka.remote.watch-failure-detector.acceptable-heartbeat-pause = 6000 s
        |akka.remote.watch-failure-detector.threshold = 6000 s
        |akka.actor.provider = "akka.remote.RemoteActorRefProvider"
        |akka.remote.netty.tcp.connection-timeout = 6000 s
        |akka.remote.netty.tcp.transport-class = "akka.remote.transport.netty.NettyTransport"
        |akka.remote.netty.tcp.host = "127.0.0.1"
        |akka.remote.netty.tcp.port = 9998
      """.stripMargin))

    val feeder = a.actorOf(Props(new ReceiverActor("akka.tcp://[email protected]:9999/user/FeederActor")), "ReceiverActor")

    println("Receiver started as:" + feeder)

    a.awaitTermination()
  }
}

class ReceiverActor[T: ClassTag](urlOfPublisher: String)
  extends Actor {

  lazy private val remotePublisher = context.actorSelection(urlOfPublisher)

  override def preStart() = remotePublisher ! SubscribeReceiver(context.self)

  def receive = {
    case msg ⇒ println(msg)
  }

  override def postStop() = remotePublisher ! UnsubscribeReceiver(context.self)

}

class FeederActor extends Actor {

  val rand = new Random()
  var receivers: mutable.LinkedList[ActorRef] = new mutable.LinkedList[ActorRef]()

  val strings: Array[String] = Array("words ", "may ", "count ")
  var i =0
  def makeMessage(): String = {
    i+=1
    val x = rand.nextInt(3)
    strings(x) + strings(2 - x) + i
  }

  /*
   * A thread to generate random messages
   */
  new Thread() {
    override def run() {
      while (true) {
        Thread.sleep(500)
        receivers.foreach(_ ! makeMessage)
      }
    }
  }.start()

  def receive: Receive = {

    case SubscribeReceiver(receiverActor: ActorRef) =>
      println("received subscribe from %s".format(receiverActor.toString))
      receivers = mutable.LinkedList(receiverActor) ++ receivers

    case UnsubscribeReceiver(receiverActor: ActorRef) =>
      println("received unsubscribe from %s".format(receiverActor.toString))
      receivers = receivers.dropWhile(x => x eq receiverActor)

  }
}

object Sender {
  def main(args: Array[String]) {

    val a = ActorSystem("a", ConfigFactory.parseString(
      """
        |akka.daemonic = on
        |akka.remote.watch-failure-detector.acceptable-heartbeat-pause = 6000 s
        |akka.remote.watch-failure-detector.threshold = 6000 s
        |akka.remote.netty.tcp.connection-timeout = 6000 s
        |akka.actor.provider = "akka.remote.RemoteActorRefProvider"
        |akka.remote.netty.tcp.transport-class = "akka.remote.transport.netty.NettyTransport"
        |akka.remote.netty.tcp.host = "127.0.0.1"
        |akka.remote.netty.tcp.port = 9999
      """.stripMargin))

    val feeder = a.actorOf(Props[FeederActor], "FeederActor")

    println("Feeder started as:" + feeder)

    a.awaitTermination()
  }
}