Scala remote actors on same machine

Question

I am new to scala and trying to use the Actor model. I have worked my way with using actors on the same machine. Now, I want to use remote actors to go a step further. As I have only one box to play with, I am planning to start a scala process which will act as a remote actor

remote.scala looks like

import scala.actors._
import scala.actors.remote._
import scala.actors.remote.RemoteActor._
import Actor._
import scala.math._
class remoteActor extends Actor{
  def act(){
    alive(9010)
    register('myActor, self)
    while (true)
    {
      println("Started Remote Actor")
        receive {
            case (caller :Actor, index :Int, length :Int) => 
            { // Do some stuff
            }
        }
    }
  }
}

object hello {
   def main(args: Array[String]): Unit = {
   println("Hello")
   val act = new remoteActor
   act.start
   }
}

The main program which will use this remote actor

actor.scala

import scala.actors._
import scala.actors.remote._
import scala.actors.remote.RemoteActor._
import Actor._
class masterActor extends Actor{
  def act()
  {
    val myRemoteActor = select(Node("localhost", 9010), 'myActor)
    myRemoteActor ! (self,3,2)
  }

}
object hello {
  def main(args: Array[String]): Unit = {
    val sample = new masterActor
    sample.start
  }

}

The problem is when I run remote.scala using eclipse (by installing the scala plugin for eclipse) I get the

Hello

Started Remote Actor

message printed in the eclipse console. But when I run the same program from Windows command line after installing scala.

C:\Program Files (x86)\scala\bin>scala remote.scala

then the messages do not get printed. However, if I change the remote.scala file to just include the hello world message, (i.e. remote.scala looks like)

object hello {
   def main(args: Array[String]): Unit = {
   println("Hello")
  }
}

then the Hello message gets printed on the Windows command prompt. Why is Windows command prompt not printing the messages in case of original remote.scala?

What I want is to start this scala process where the remote actor is registered and the process is still alive. I then want to start the main.scala program from another command prompt so that it sends messages to the remote actor to perform the computations. How can I make sure that the remote actor is still alive and registered and the process is running?

Answer 1

Don't include the actor reference in your message. The receiving pattern should be:

receive {
  case (index :Int, length :Int) => 
    { // Do some stuff
    }
}

And the message should be sent as myRemoteActor ! (3,2)

In the receiver you can just write sender to refer to the original message sender. There are other useful functions, e.g. reply(msg) - replies to the original sender with msg