尝试连接到远程actor时的Akka BindException:地址已在使用中

Question

我正在试验Akka远程演员,试图通过网络建立一个简单的2人游戏.这个回答前面一个问题给了我一个很好的起点,但我现在有一个很难理解如何使其适应我的处境.ISTM原始连接两次来自同一客户端(请参阅下面的评论部分).我想要做的是从不同的客户端运行两次,但是当我这样做时,我得到一个BindException,地址已经在使用中.我猜那是因为每次运行代码都会尝试启动服务器？我需要一种情况,我可以独立于连接和断开连接的客户端启动和停止主演员.(最小)Akka配置和异常在代码之后:

import akka.actor._
//example from answer to https://stackoverflow.com/questions/15527193/keeping-references-to-two-actors
// by Patrick Nordwall
case object JoinMsg
case class Msg(s: String)

class Server extends Actor {

  def receive = {
    case JoinMsg =>
      println("got player 1")
      sender ! Msg("Waiting for player 2")
      context.become(waitingForPlayer2(sender))
  }

  def waitingForPlayer2(client1: ActorRef): Actor.Receive = {
    case JoinMsg =>
      println("got player 2")
      sender ! Msg("hi")
      client1 ! Msg("hi")
      context.become(ready(client1, sender))
  }

  def ready(client1: ActorRef, client2: ActorRef): Actor.Receive = {
    case m: Msg if sender == client1 => client2 ! m
    case m: Msg if sender == client2 => client1 ! m
  }
}

/* I want to run this once for each "player" */
object Demo extends App {
  val system = ActorSystem("Game")
  val server = system.actorOf(Props[Server], "server")

  system.actorOf(Props(new Actor {
    server ! JoinMsg
    def receive = {
      case Msg(s) => println(s)
    }
  }))

  /* Rather than connecting twice from the same node, I want to run this
     program twice from different nodes 
    system.actorOf(Props(new Actor {
    server ! JoinMsg
    def receive = {
      case Msg(s) => println(s)
    }
  }))*/
}

配置:

akka {
  actor {
    provider = "akka.remote.RemoteActorRefProvider"
  }
  remote {
    transport = "akka.remote.netty.NettyRemoteTransport"
    netty {
      hostname = "localhost"
      port = 9000
    }
 }
}

例外:

Exception in thread "main" java.lang.ExceptionInInitializerError
    at akkademo.main(akkademo.scala)
Caused by: org.jboss.netty.channel.ChannelException: Failed to bind to: localhost/127.0.0.1:9000
    at org.jboss.netty.bootstrap.ServerBootstrap.bind(ServerBootstrap.java:298)
    at akka.remote.netty.NettyRemoteServer.start(Server.scala:54)
    at akka.remote.netty.NettyRemoteTransport.start(NettyRemoteSupport.scala:90)
    at akka.remote.RemoteActorRefProvider.init(RemoteActorRefProvider.scala:94)
    at akka.actor.ActorSystemImpl._start(ActorSystem.scala:588)
    at akka.actor.ActorSystemImpl.start(ActorSystem.scala:595)
    at akka.actor.ActorSystem$.apply(ActorSystem.scala:111)
    at akka.actor.ActorSystem$.apply(ActorSystem.scala:93)
    at akkademo$.<init>(akkademo.scala:4)
    at akkademo$.<clinit>(akkademo.scala)
    ... 1 more
Caused by: java.net.BindException: Address already in use

TIA.

Answer 1

在同一台计算机上运行多个实例时,需要为它们配置不同的端口.在此示例中,只有服务器需要知道端口(9000).对于客户端,您可以将0用于随机可用端口.

为客户端定义另一个配置文件.client.conf:

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

ActorSystem使用此配置在客户端中启动:

import com.typesafe.config.ConfigFactory
val system = ActorSystem("Game", ConfigFactory.load("client"))

在客户端中,您将使用以下命令查找服务器:

val server = system.actorFor("akka://Game@localhost:9000/user/server")