CODEWITHSUNDEEP
akka
Puneeth Reddy V
Puneeth Reddy V

Reputation: 1568

How and when to use ActorIdentity in Akka

Can anyone explain how and when to use ActorIdentity with a good example?

From documents I can find that "There is a built-in Identify message that all Actors will understand and automatically reply to with a ActorIdentity message containing the ActorRef".

Does that statement mean obtained actor say actorSelector have ActorIdentity message wrapped in my actor? 

ActorSelection actorSelector =  getContext().actorSelection("/A/B/*");

Upvotes: 5

Views: 740

Answers (1)

sourcedelica
sourcedelica

Reputation: 24040

When you send an Identify message to an ActorSelection the actor will respond, if it exists, with an ActorIdentity message.

If the actor exists the ActorIdentity message will contain a Some(actorRef). It is more efficient to send messages to ActorRefs than ActorSelections.

For example (from the manual):

class Follower extends Actor {
  val identifyId = 1
  context.actorSelection("/user/another") ! Identify(identifyId)

  def receive = {
    case ActorIdentity(`identifyId`, Some(ref)) =>
      context.watch(ref)
      context.become(active(ref))
    case ActorIdentity(`identifyId`, None) => context.stop(self)

  }

  def active(another: ActorRef): Actor.Receive = {
    case Terminated(`another`) => context.stop(self)
  }
}

The section in the manual that covers this is called Identifying Actors via Actor Selection.

Upvotes: 5

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