Scala Italy 2015: An Introduction to Akka and the Actor-Based Model: Demo. See article http://danielasfregola.com/2015/05/11/scala-italy-2015-highlights/

demo-part1.scala

import akka.actor._

class SimpleActor extends Actor {

  def receive = {
    case msg => println(s"${self.path} - $msg")
  }

}

/** Main **/

val system = ActorSystem("intro-akka-demo")

val simpleActor = system.actorOf(Props[SimpleActor], name = "simple")

simpleActor ! "Yo! This is a message"
// akka://intro-akka-demo/user/simple - Yo! This is a message

simpleActor ! List(1,2,3)
// akka://intro-akka-demo/user/simple - List(1, 2, 3)

demo-part2.scala

import akka.actor._

case class Person(name: String)

class HelloActor extends Actor {
  import context._

  def receive = inEnglish
  
  def inEnglish: Receive = {
    case p: Person => {
      println(s"${self.path} - Hello ${p.name}!")
      become(inItalian)
    }
  }
  
  def inItalian: Receive = {
    case p: Person => {
      println(s"${self.path} - Ciao ${p.name}!")
      become(inEnglish)
    }
  }

}

/** Main **/

val system = ActorSystem("intro-akka-demo")

val helloActor = system.actorOf(Props[HelloActor], name = "hello")

helloActor ! "This should be ignored"

helloActor ! Person("Martin")
// akka://intro-akka-demo/user/hello - Hello Martin

helloActor ! Person("Scala Italy")
// akka://intro-akka-demo/user/hello - Ciao Scala Italy!

helloActor ! Person("Daniela")
// akka://intro-akka-demo/user/hello - Hello Daniela!

demo-part3.scala

import akka.actor._
import akka.actor.SupervisorStrategy._

case class Person(name: String)

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

class HelloActor extends Actor {
  import context._
  
  override def preRestart(reason: Throwable, message: Option[Any]) = {
    println(s"${self.path} - Yo, I am restarting...")
    super.preRestart(reason, message)
  }

  override def postRestart(reason: Throwable) = {
    println(s"${self.path} -...restart completed!")
    super.postRestart(reason)
  }
  
  def receive = inEnglish orElse crashIfUnknown
  
  def inEnglish: Receive = {
    case p: Person => {
      println(s"${self.path} - Hello ${p.name}!")
      become(inItalian orElse crashIfUnknown)
    }
  } 
  
  def inItalian: Receive = {
    case p: Person => {
      println(s"${self.path} - Ciao ${p.name}!")
      become(inEnglish orElse crashIfUnknown)
    }
  }
  
  def crashIfUnknown: Receive = {
    case _ => throw new RuntimeException("BOOM!")
  }

}

class HelloActorSupervisor extends Actor {

  override def supervisorStrategy = OneForOneStrategy() {
    case _: RuntimeException => Restart
  }

  val helloActor = context.actorOf(Props[HelloActor], "hello")

  override def receive: Receive = {
    case msg => helloActor forward msg
  }
}

/** Main **/

val system = ActorSystem("intro-akka-demo")

val helloSupervisor = system.actorOf(Props[HelloActorSupervisor], name = "hello-supervisor")


helloSupervisor ! Person("Martin")
// akka://intro-akka-demo/user/hello-supervisor/hello - Hello Martin

helloSupervisor ! Person("Scala Italy")
// akka://intro-akka-demo/user/hello-supervisor/hello - Ciao Scala Italy!

helloSupervisor ! Person("Daniela")
// akka://intro-akka-demo/user/hello-supervisor/hello - Hello Daniela!

helloSupervisor ! "This should crash the actor"
// akka://intro-akka-demo/user/hello-supervisor/hello - Yo, I am restarting...
// akka://intro-akka-demo/user/hello-supervisor/hello -...restart completed!

//  ERROR [OneForOneStrategy]: BOOM!
//    java.lang.RuntimeException: BOOM!
//    at HelloActor$$anonfun$crashIfUnknown$1.applyOrElse(demo-part3.scala:51) ~[classes/:na]
//  at scala.PartialFunction$OrElse.applyOrElse(PartialFunction.scala:171) ~[scala-library-2.11.5.jar:na]
//  at akka.actor.Actor$class.aroundReceive(Actor.scala:465) ~[akka-actor_2.11-2.3.9.jar:na]
//  at HelloActor.aroundReceive(demo-part3.scala:21) ~[classes/:na]
//  at akka.actor.ActorCell.receiveMessage(ActorCell.scala:516) [akka-actor_2.11-2.3.9.jar:na]
//  at akka.actor.ActorCell.invoke(ActorCell.scala:487) [akka-actor_2.11-2.3.9.jar:na]
//  at akka.dispatch.Mailbox.processMailbox(Mailbox.scala:254) [akka-actor_2.11-2.3.9.jar:na]
//  at akka.dispatch.Mailbox.run(Mailbox.scala:221) [akka-actor_2.11-2.3.9.jar:na]
//  at akka.dispatch.Mailbox.exec(Mailbox.scala:231) [akka-actor_2.11-2.3.9.jar:na]
//  at scala.concurrent.forkjoin.ForkJoinTask.doExec(ForkJoinTask.java:260) [scala-library-2.11.5.jar:na]
//  at scala.concurrent.forkjoin.ForkJoinPool$WorkQueue.runTask(ForkJoinPool.java:1339) [scala-library-2.11.5.jar:na]
//  at scala.concurrent.forkjoin.ForkJoinPool.runWorker(ForkJoinPool.java:1979) [scala-library-2.11.5.jar:na]
//  at scala.concurrent.forkjoin.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:107) [scala-library-2.11.5.jar:na]

helloSupervisor ! Person("Martin")
// akka://intro-akka-demo/user/hello-supervisor/hello - Hello Martin!