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What is ActorRef in akka?

What is ActorRef in akka?

abstract class ActorRef extends Comparable[ActorRef] with Serializable. Immutable and serializable handle to an actor, which may or may not reside on the local host or inside the same akka. actor. An ActorRef can be obtained from an akka. actor.

What is Sender () in akka?

You can reply to a message by using sender() method. This method gives you ActorRef which is a instance of sender Actor. If there is no sender i.e. a message which is sent without an actor or future context, the default sender is a ‘dead-letter’ actor reference. …

How do you make an ActorRef?

An ActorRef can be obtained from an ActorRefFactory, an interface which is implemented by ActorSystem and ActorContext. This means actors can be created top-level in the ActorSystem or as children of an existing actor, but only from within that actor.

What is actor system in akka?

An ActorSystem is a hierarchical group of actors which share common configuration, e.g. dispatchers, deployments, remote capabilities and addresses. It is also the entry point for creating or looking up actors. ActorSystem provides an actorOf() method which is used to create actor instance.

Why is Akka typed?

The new Actor APIs are known as Akka Typed because–unlike before–the actors must declare what messages types they can handle. Messages are sent via a location transparent handle to the actor, so called ActorRef .

What is Scala actor?

The Actor Model provides a higher level of abstraction for writing concurrent and distributed systems. It alleviates the developer from having to deal with explicit locking and thread management, making it easier to write correct concurrent and parallel systems.

How can I send a message to an actor in akka?

Akka Actor tell() Method Example2

  1. import{Actor,ActorSystem, Props};
  2. class ActorExample extends Actor{
  3. def receive = {
  4. case message:String => println(“Message received: “+message+ ” from – “+;
  5. println(“Sender: “+sender())
  6. var child = context.actorOf(Props[Actor2], “ChildActor”);
  7. child ! ”
  8. }

How do you stop akka actor?

In Akka, you can stop Actors by invoking the stop() method of either ActorContext or ActorSystem class. ActorContext is used to stop child actor and ActorSystem is used to stop top level Actor. The actual termination of the actor is performed asynchronously.

Why do we need Akka?

Akka gives developers a unified way to build scalable and fault-tolerant software that can scale up on multicore systems, and scale out in distributed computing environments, which today often means in the cloud. This makes it simple to write software that can scale with the needs of the application.

How do Akka actors communicate?

Actors are reactive and message driven. Actors communicate using asynchronous messages. This ensures that the sender does not stick around waiting for their message to be processed by the recipient. Instead, the sender puts the message in the recipient’s mailbox and is free to do other work.

Why is Akka not popular?

In general we recommend against using Akka Cluster and actor messaging between different services because that would result in a too tight code coupling between the services and difficulties deploying these independent of each other, which is one of the main reasons for using a microservices architecture.

Why Akka is bad?

When to use sink or actorref in Akka?

Using Sink.actorRef or ordinary tell from a map or foreach operator means that there is no back-pressure signal from the destination actor, i.e. if the actor is not consuming the messages fast enough the mailbox of the actor will grow, unless you use a bounded mailbox with zero mailbox-push-timeout-time or use a rate limiting operator in front.

How to use the new Akka actor APIs?

You are viewing the documentation for the new actor APIs, to view the Akka Classic documentation, see Classic Actors. To use Akka Actors, add the following dependency in your project:

Where does get published to?

Otherwise an (message, sender, recipient) will be published to the ActorSystem ‘s EventStream. Note further that the return type of the behavior defined above is Unit; if the actor shall reply to the received message then this must be done explicitly as explained below.

What happens if the actor is stopped in Akka?

In case the target actor is stopped, the operator will fail with an AskStageTargetActorTerminatedException The stream can be completed with failure by sending as reply from the actor. If the ask fails due to timeout the stream will be completed with TimeoutException failure.