CrossActorSystemMessageTest.scala

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

import scala.reflect.ClassTag

object CrossActorSystemMessageTest {
  def main(args: Array[String]): Unit = {
    val fooActorSystem = ActorSystem("foo")
    val barActorSystem = ActorSystem("bar")

    val foo = fooActorSystem.mkActor("fooActor", new Foo)
    val bar = barActorSystem.mkActor("barActor", new Bar(foo))

    bar ! ()

    fooActorSystem.awaitTermination()
    barActorSystem.awaitTermination()

    fooActorSystem.shutdown()
    barActorSystem.shutdown()
  }

  class Foo extends Actor {
    def receive = {
      case "Hi Foo" => println("FUCKING SUCCESS!!")
    }
  }

  class Bar(foo: ActorRef) extends Actor {
    def receive = {
      case () => foo ! "Hi Foo"
    }
  }

  implicit class ActorSystemW(val actorSystem: ActorSystem) extends AnyVal {
    def mkActor[T <: Actor: ClassTag](name: String, creator: => T): ActorRef = actorSystem.actorOf(Props(creator), name)
  }
}