无法与Akka建立远程通信

Question

我最近才开始使用 Akka 和 Scala，我正在尝试制作一个实现基本 Akka 远程处理的简单项目。

当我在不远程的情况下尝试以下代码时一切正常，但是当我将数据库 actor 放在远程 actor 系统上但仍在同一台机器中时，出现错误 "deadletters encountered"

这是将数据存储在哈希图中的数据库参与者的代码：

class ActorDB extends Actor {

  val data = new HashMap[String, Object]
  val log = Logging(context.system, this)

  override def receive = {
      case Set(key, value) =>
        log.info("received the pair:" + key +","+ value)
        data.put(key, value)
        sender() ! Status.Success

      case Get(key) =>
      val value = data.get(key)
        value match {
          case Some(v) =>
            log.info("found the pair"+ key + "," + v)
            sender() ! v
          case None =>
            log.info("the key:" + key + ", has no corresponding value in the database")
            sender() ! Status.Failure(KeyNotFoundException(key))
      }

      case _ => Status.Failure(new ClassNotFoundException)
  }
}

object Main extends App {

  val config =  ConfigFactory.parseString(
    """
      |akka {
      |  actor {
      |    provider = "akka.remote.RemoteActorRefProvider"
      |  }
      |  remote {
      |    enabled-transports = ["akka.remote.netty.tcp"]
      |    netty.tcp {
      |      hostname = "127.0.0.1"
      |      port = 2552
      |    }
      |  }
      |}
    """.stripMargin)


  val system = ActorSystem("AkkaIMDB", ConfigFactory.load(config))
  val database = system.actorOf(Props(new ActorDB),"ImdbActor")
}

这是客户端的代码

object main extends App {

  implicit val timeout = Timeout(1 seconds)

  val config =  ConfigFactory.parseString(
    """
      |akka {
      |  actor {
      |    provider = "akka.remote.RemoteActorRefProvider"
      |  }
      |  remote {
      |    enabled-transports = ["akka.remote.netty.tcp"]
      |    netty.tcp {
      |      hostname = "127.0.0.1"
      |      port = 2553
      |    }
      |  }
      |}
    """.stripMargin)
  val system = ActorSystem("ClientSystem", ConfigFactory.load(config))
  val DBreference = system.actorSelection(s"AkkaIMDB@127.0.0.1:2552/user/ImdbActor")

  var key: String = ""
  var value: Object = None

    println("Type S to send or R to receive a (key value) pair")
    StdIn.readLine() match {
      case "S" => {
        println("print key: ")
        key = StdIn.readLine()
        println("print value: ")
        value = StdIn.readLine()
        (DBreference ? messages.Set(key , value)).map({case akka.actor.Status.Success => println("Data added successfully")})
      }
      case "R" => {
        println("print key: ")
        key = StdIn.readLine()
        (DBreference ? messages.Get(key)).map(
          {case akka.actor.Status.Failure(KeyNotFoundException(k)) => println(s"No pair has been found with the key $k")
          case v => println(s"the key $key corresponds to the value $v")} )
      }
      case _ => {}
    }

}

Answer 1

您程序中的所有内容都是正确的，除了您 LocalApplication 中的演员选择应该如下所示：

val DBreference = system.actorSelection(s"akka.tcp://AkkaIMDB@127.0.0.1:2552/user/ImdbActor")

更新后它应该可以工作。

永远记住，actor 的 url 以协议名称 akka.tcp:// 开头。

无法与Akka建立远程通信

Cannot establish remote communication with Akka

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