AKKA Remote Actor Error

Question

I am trying to run an AKKA remote example by

1. Running the remote actor in a machine with IP 192.168.1.7
2. Running the local from my machine

The remote actor is started up in the machine (with ip address 192.168.1.7); but when I start Local actor from my machine, its not able to connect to the remote actor. Please find the Local and Remote actor system configuration:

Local:

akka {
  //loglevel = "INFO"
  actor {
    provider = "akka.remote.RemoteActorRefProvider"
  }
  remote {
    enabled-transports = ["akka.remote.netty.tcp"]
    netty.tcp {
      hostname = "127.0.0.1"
      port = 0
    }
    //log-sent-messages = on
    //log-received-messages = on
  }
}

Remote:

akka {
  //loglevel = "INFO"
  actor {
    provider = "akka.remote.RemoteActorRefProvider"
  }
  remote {
    enabled-transports = ["akka.remote.netty.tcp"]
    netty.tcp {
      hostname = "127.0.0.1"
      port = 5150
    }
    //log-sent-messages = on
    //log-received-messages = on
  }
}

Code in the local system to connect to remote actor:

class LocalActor extends Actor {
  val remote = context.actorFor("akka.tcp://[email protected]:5150/user/RemoteActor")
  var counter = 0
  def receive = {
    case "START" => 
        remote ! "Hello from the LocalActor"
    case msg: String => 
        println(s"LocalActor received message: '$msg'")
        if (counter < 5) {
            sender ! "Hello back to you"
            counter += 1
        }
  }
}  

When I start the local system, I get the below Message:

C:\Users\AnandKrishnan\Documents\GitHub\AkkaRemoteActorsHelloWorld\HelloLocal [master +0 ~5 -0]> sbt run
Java HotSpot(TM) 64-Bit Server VM warning: ignoring option MaxPermSize=256m; support was removed in 8.0
[info] Set current project to HelloLocal (in build file:/C:/Users/AnandKrishnan/Documents/GitHub/AkkaRemoteActorsHelloWorld/HelloLocal/)
[info] Compiling 1 Scala source to C:\Users\AnandKrishnan\Documents\GitHub\AkkaRemoteActorsHelloWorld\HelloLocal\target\scala-2.11\classes...
[warn] there was one deprecation warning; re-run with -deprecation for details
[warn] one warning found
[info] Running local.Local
[INFO] [02/14/2016 22:57:11.755] [run-main-0] [Remoting] Starting remoting
[INFO] [02/14/2016 22:57:12.163] [run-main-0] [Remoting] Remoting started; listening on addresses :[akka.tcp://[email protected]:50830]
[INFO] [02/14/2016 22:57:12.163] [run-main-0] [Remoting] Remoting now listens on addresses: [akka.tcp://[email protected]:50830]
[WARN] [02/14/2016 22:57:13.351] [LocalSystem-akka.remote.default-remote-dispatcher-5] [akka.tcp://[email protected]:50830/system/endpointManager/reliableEndpointWriter-akka.tcp
%3A%2F%2FHelloRemoteSystem%40192.168.1.7%3A5150-0/endpointWriter] AssociationError [akka.tcp://[email protected]:50830] -> [akka.tcp://[email protected]:5150]: Error
 [Invalid address: akka.tcp://[email protected]:5150] [
akka.remote.InvalidAssociation: Invalid address: akka.tcp://[email protected]:5150
Caused by: akka.remote.transport.Transport$InvalidAssociationException: Connection refused: no further information: /192.168.1.7:5150
]
[WARN] [02/14/2016 22:57:13.371] [LocalSystem-akka.remote.default-remote-dispatcher-6] [Remoting] Tried to associate with unreachable remote address [akka.tcp://[email protected]:5150]. Address is now gated for 5000 ms, all messages to this address will be delivered to dead letters. Reason: Connection refused: no further information: /192.168.1.7:5150
[INFO] [02/14/2016 22:57:13.389] [LocalSystem-akka.actor.default-dispatcher-3] [akka://LocalSystem/deadLetters] Message [java.lang.String] from Actor[akka://LocalSystem/user/LocalActor#1441959988] to Actor[akka://LocalSystem/deadLetters] was not delivered. [1] dead letters encountered. This logging can be turned off or adjusted with configuration settings 'akka.log-dead-letters' and 'akka.log-dead-letters-during-shutdown'.

Answer 1

In order for an Akka actor system to communicate with other hosts, the actor system must bind to a hostname or IP that is routable by the other host in question. localhost, of course, is not.

Your remote system needs to bind to 192.168.1.7:

akka {
  remote {
    netty.tcp {
      hostname = "192.168.1.7"
    }
  }
}

Of course in production you'll likely want to use hostnames rather than IPs.

Answer 2

In the Remote Actor class you have:

val system = ActorSystem("HelloRemoteSystem", config)

Make sure that in the Local actor when using actorSelection/actorFor you use the same name like:

val remoteActor = context.actorSelection("akka.tcp://[email protected]:2553/user/RemoteActor")