Question

I am trying to connect a remote akka system to a play framework and it looks like I am having a problem with the configuration.

I have a Play framework controller class and an Akka actor as the local objects below are the codes:

when I run the following message is displayed on the web page

[ClassNotFoundException: akka.remote.RemoteActorRefProvider]
In C:\Users\FAISAL\workspace\Rakka\app\controllers\Application.java at line 21.
17  public static Result index() throws InterruptedException { 
18    
19    System.out.println(" Local Node Called0");
20    
21    ActorSystem csystem = ActorSystem.create("Application", ConfigFactory.load().getConfig("LocalNode"));
22    ActorRef localNode = csystem.actorOf(new Props(LocalNode.class));
23
24      System.out.println(" Local Node Called1");
25      localNode.tell("Hello");

this is the controller:

public class Application extends Controller {



  public static Result index() throws InterruptedException { 

      System.out.println(" Local Node Called0");

      ActorSystem csystem = ActorSystem.create("Application", ConfigFactory.load().getConfig("LocalNode"));
      ActorRef localNode = csystem.actorOf(new Props(LocalNode.class));

        System.out.println(" Local Node Called1");
        localNode.tell("Hello World");
        System.out.println(" Local Node Called2");

        Thread.sleep(5000);
        csystem.shutdown();
        return ok(index.render("I am OK"));
  }    
}

this is the LOcal Akka actor

public class LocalNode extends UntypedActor {

    LoggingAdapter log = Logging.getLogger(getContext().system(), this);
    Timeout timeout = new Timeout(Duration.parse("5 seconds"));

    ActorRef master;

    public void preStart()
    {
        /* Get reference to Master Node*/
         master = getContext().actorFor("akka://MasterNode@127.0.0.1:2552/user/master");
    }

    @Override
    public void onReceive(Object message) throws Exception {
        System.out.println(" Future called  ");

         Future<Object> future = Patterns.ask(master , message.toString(), timeout);

            String result = (String) Await.result(future, timeout.duration());

            log.info("Messagefrom Server", result); 
    }

}

this is the local play conf file

#confige the remote connection

LocalNode {
    akka {
        actor {
            provider = "akka.remote.RemoteActorRefProvider"
        }
        remote {
            transport = "akka.remote.netty.NettyRemoteTransport"
            netty {
                hostname = "127.0.0.1"
                port = 0
            }
        }
    }
}

the code below is from the remote akka system.

this is the remote master

public class MasterNode implements Bootable
{
     final ActorSystem system;

      public MasterNode() {
        system = ActorSystem.create("MasterNode", ConfigFactory.load()
            .getConfig("master"));
        ActorRef actor = system.actorOf(new Props(MasterActor.class),"master");
        System.out.println(" Master Node is called ");
      }

      public void startup() {

      }

          public void shutdown() {
            system.shutdown();
          }
}  

this is the remote akka actor system

public class MasterActor extends UntypedActor {

    @Override
    public void onReceive(Object message) throws Exception {


         if (message instanceof String) {
                // Get reference to the message sender and reply back
                getSender().tell(message + " got something");       
    }
  }  
}

this is from the remote akka config

master {
akka {
  actor {
    provider = "akka.remote.RemoteActorRefProvider"
  }
  remote {
    transport = "akka.remote.netty.NettyRemoteTransport"
    netty {
      hostname = "127.0.0.1"
      port = 2552
    }
 }
}}

To run the system , I first start the Akka remote system and then
start the Play 2 framework

after running the Play framewrok , I get the following error

[info] play - Application started (Dev)
 Local Node Called0
[error] application -

! @6bol84j48 - Internal server error, for request [GET /] ->

play.core.ActionInvoker$$anonfun$receive$1$$anon$1: Execution exception [[ClassN
otFoundException: akka.remote.RemoteActorRefProvider]]
        at play.core.ActionInvoker$$anonfun$receive$1.apply(Invoker.scala:134) [
play_2.9.1.jar:2.0.2]
        at play.core.ActionInvoker$$anonfun$receive$1.apply(Invoker.scala:115) [
play_2.9.1.jar:2.0.2]
        at akka.actor.Actor$class.apply(Actor.scala:318) [akka-actor.jar:2.0.2]
        at play.core.ActionInvoker.apply(Invoker.scala:113) [play_2.9.1.jar:2.0.
2]
        at akka.actor.ActorCell.invoke(ActorCell.scala:626) [akka-actor.jar:2.0.
2]
        at akka.dispatch.Mailbox.processMailbox(Mailbox.scala:197) [akka-actor.j
ar:2.0.2]
Caused by: java.lang.ClassNotFoundException: akka.remote.RemoteActorRefProvider
        at java.net.URLClassLoader$1.run(Unknown Source) ~[na:1.7.0_01]
        at java.net.URLClassLoader$1.run(Unknown Source) ~[na:1.7.0_01]
        at java.security.AccessController.doPrivileged(Native Method) ~[na:1.7.0
_01]
        at java.net.URLClassLoader.findClass(Unknown Source) ~[na:1.7.0_01]
        at java.lang.ClassLoader.loadClass(Unknown Source) ~[na:1.7.0_01]
        at java.lang.ClassLoader.loadClass(Unknown Source) ~[na:1.7.0_01]

looks like am not getting something right please any suggestion or help will be welcomed.

Answer 1

Maybe you forgot to add the dependency to Akka remote in your Play2 application.

If you’re using Play 2.0.3, add the following dependency in your project/Build.scala file:

val appDependencies = Seq(
      "com.typesafe.akka" % "akka-remote" % "2.0.2"
)