Actor base trait that should be extended by or mixed to create an Actor with the semantics of the 'Actor Model': https://en.wikipedia.org/wiki/Actor_model

An actor has a well-defined (non-cyclic) life-cycle.

• RUNNING (created and started actor) - can receive messages
• SHUTDOWN (when 'stop' is invoked) - can't do anything

The Actor's own akka.actor.ActorRef is available as self, the current message’s sender as sender() and the akka.actor.ActorContext as context. The only abstract method is receive which shall return the initial behavior of the actor as a partial function (behavior can be changed using context.become and context.unbecome).

This is the Scala API (hence the Scala code below), for the Java API see akka.actor.AbstractActor.

class ExampleActor extends Actor {

  override val supervisorStrategy = OneForOneStrategy(maxNrOfRetries = 10, withinTimeRange = 1 minute) {
    case _: ArithmeticException      => Resume
    case _: NullPointerException     => Restart
    case _: IllegalArgumentException => Stop
    case _: Exception                => Escalate
  }

  def receive = {
                                     // directly calculated reply
    case Request(r)               => sender() ! calculate(r)

                                     // just to demonstrate how to stop yourself
    case Shutdown                 => context.stop(self)

                                     // error kernel with child replying directly to 'sender()'
    case Dangerous(r)             => context.actorOf(Props[ReplyToOriginWorker]).tell(PerformWork(r), sender())

                                     // error kernel with reply going through us
    case OtherJob(r)              => context.actorOf(Props[ReplyToMeWorker]) ! JobRequest(r, sender())
    case JobReply(result, orig_s) => orig_s ! result
  }
}

The last line demonstrates the essence of the error kernel design: spawn one-off actors which terminate after doing their job, pass on sender() to allow direct reply if that is what makes sense, or round-trip the sender as shown with the fictitious JobRequest/JobReply message pair.

If you don’t like writing context you can always import context._ to get direct access to actorOf, stop etc. This is not default in order to keep the name-space clean.