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8 Remote Actors

8.1 Creating remote actors

import scala.actors.Actor
import Actor._
import scala.actors.remote.RemoteActor.{alive, register}

class ChatRoom extends Actor {
  def act() {
    alive(9000)
    register('chatroom, self)
    loop {
      receive {
        case Subscribe(user) =>       // handle subscriptions
        case Unsubscribe(user) =>     // handle unsubscriptions
        case UserPost(user, post) =>  // handle user posts
      }
    }
  }
}


def register(name: Symbol, a: Actor): Unit


  

8.2 Remote communication

def select(node: Node, sym: Symbol): AbstractActor


case class Node(address: String, port: Int)


val chatRoom = select(Node("127.0.0.1", 9000), 'chatroom)


chatRoom ! Subscribe(User("Alice"))
chatRoom !? Subscribe(User("Bob"))
val future = chatRoom !! Subscribe(User("Charly"))
...


  

8.3 A remote start service

case class Start(clazz: Class[_ <: Actor])
case object Stop


class Server extends Actor {
  var numStarted = 0
  def act() {
    alive(19000)
    register('server, this)
    println("remote start server running...")
    loop {
      react {
        case Start(clazz) =>
          val a: Actor = clazz.newInstance()
          a.start()
          numStarted += 1
          reply()
        case Stop =>
          println("remote start server started " +
                  numStarted + " remote actors")
          exit()
      }
    }
  }
}


class EchoActor extends Actor {
  def act() {
    alive(19000)
    register('echo, this)
    react {
      case any => reply("echo: " + any)
    }
  }
}


val server = select(Node("localhost", 19000), 'server)
server !? Start(classOf[EchoActor])
val echo = select(Node("localhost", 19000), 'echo)
val resp = echo !? "hello"
println("remote start client received " + resp)


remote start client received echo: hello