Akka/Scala example source code file (LookupActor.java)

This example Akka source code file (LookupActor.java) is included in my "Source Code Warehouse" project. The intent of this project is to help you more easily find Akka and Scala source code examples by using tags.

All credit for the original source code belongs to akka.io; I'm just trying to make examples easier to find. (For my Scala work, see my Scala examples and tutorials.)

Akka tags/keywords

actor, actoridentity, add, akka, concurrent, duration, exception, identify, lookupactor, override, procedure, receivetimeout, remote, seconds, time, untypedactor

The LookupActor.java Akka example source code

package sample.remote.calculator;

import static java.util.concurrent.TimeUnit.SECONDS;
import scala.concurrent.duration.Duration;
import akka.actor.ActorRef;
import akka.actor.ActorIdentity;
import akka.actor.Identify;
import akka.actor.Terminated;
import akka.actor.UntypedActor;
import akka.actor.ReceiveTimeout;
import akka.japi.Procedure;

public class LookupActor extends UntypedActor {

  private final String path;
  private ActorRef calculator = null;

  public LookupActor(String path) {
    this.path = path;
    sendIdentifyRequest();
  }

  private void sendIdentifyRequest() {
    getContext().actorSelection(path).tell(new Identify(path), getSelf());
    getContext()
        .system()
        .scheduler()
        .scheduleOnce(Duration.create(3, SECONDS), getSelf(),
            ReceiveTimeout.getInstance(), getContext().dispatcher(), getSelf());
  }

  @Override
  public void onReceive(Object message) throws Exception {
    if (message instanceof ActorIdentity) {
      calculator = ((ActorIdentity) message).getRef();
      if (calculator == null) {
        System.out.println("Remote actor not available: " + path);
      } else {
        getContext().watch(calculator);
        getContext().become(active, true);
      }

    } else if (message instanceof ReceiveTimeout) {
      sendIdentifyRequest();

    } else {
      System.out.println("Not ready yet");

    }
  }

  Procedure<Object> active = new Procedure<Object>() {
    @Override
    public void apply(Object message) {
      if (message instanceof Op.MathOp) {
        // send message to server actor
        calculator.tell(message, getSelf());

      } else if (message instanceof Op.AddResult) {
        Op.AddResult result = (Op.AddResult) message;
        System.out.printf("Add result: %d + %d = %d\n", result.getN1(),
            result.getN2(), result.getResult());

      } else if (message instanceof Op.SubtractResult) {
        Op.SubtractResult result = (Op.SubtractResult) message;
        System.out.printf("Sub result: %d - %d = %d\n", result.getN1(),
            result.getN2(), result.getResult());

      } else if (message instanceof Terminated) {
        System.out.println("Calculator terminated");
        sendIdentifyRequest();
        getContext().unbecome();

      } else if (message instanceof ReceiveTimeout) {
        // ignore

      } else {
        unhandled(message);
      }

    }
  };
}