Akka-http：连接到本地主机上的 websocket

Question

我正在尝试通过本地主机上的 websocket 连接到某个服务器。当我尝试通过

在 JS 中做到这一点时

ws = new WebSocket('ws://localhost:8137');

成功了。但是，当我使用 akka-http 和 akka-streams 时，出现 "connection failed" 错误。

object Transmitter {
    implicit val system: ActorSystem = ActorSystem()
    implicit val materializer: ActorMaterializer = ActorMaterializer()

    import system.dispatcher

    object Rec extends Actor {
        override def receive: Receive = {
            case TextMessage.Strict(msg) =>
                Log.info("Recevied signal " + msg)
        }
    }

    //  val host = "ws://echo.websocket.org"
    val host = "ws://localhost:8137"

    val sink: Sink[Message, NotUsed] = Sink.actorRef[Message](system.actorOf(Props(Rec)), PoisonPill)


    val source: Source[Message, NotUsed] = Source(List("test1", "test2") map (TextMessage(_)))


    val flow: Flow[Message, Message, Future[WebSocketUpgradeResponse]] =
        Http().webSocketClientFlow(WebSocketRequest(host))

    val (upgradeResponse, closed) =
        source
        .viaMat(flow)(Keep.right) // keep the materialized Future[WebSocketUpgradeResponse]
        .toMat(sink)(Keep.both) // also keep the Future[Done]
        .run()

    val connected: Future[Done.type] = upgradeResponse.flatMap { upgrade =>
        if (upgrade.response.status == StatusCodes.SwitchingProtocols) {
            Future.successful(Done)
        } else {
            Future.failed(new Exception(s"Connection failed: ${upgrade.response.status}")
        }
    }

    def test(): Unit = {
        connected.onComplete(Log.info)
    }
}

ws://echo.websocket.org.

完全正常

我认为附加我的服务器代码是没有道理的，因为它适用于 JavaScript 客户端，问题仅在于连接，但是如果您想查看它，我可以展示它。

我做错了什么？

Answer 1

我已经使用来自 akka documentation 的 websocket 服务器测试了您的客户端实现，而且我没有收到任何连接错误。您的 websocket 客户端连接成功。这就是为什么我猜测问题出在您的服务器实现上。

object WebSocketServer extends App {
  implicit val system = ActorSystem()
  implicit val materializer = ActorMaterializer()
  import Directives._

  val greeterWebSocketService = Flow[Message].collect {
    case tm: TextMessage => TextMessage(Source.single("Hello ") ++ tm.textStream)
  }

  val route =
    get {
      handleWebSocketMessages(greeterWebSocketService)
    }

  val bindingFuture = Http().bindAndHandle(route, "localhost", 8137)

  println(s"Server online at http://localhost:8137/\nPress RETURN to stop...")
  StdIn.readLine()

  import system.dispatcher // for the future transformations
  bindingFuture
    .flatMap(_.unbind()) // trigger unbinding from the port
    .onComplete(_ => system.terminate()) // and shutdown when done
}

顺便说一下，我注意到您的 actor 的 receive 方法没有涵盖所有可能的消息。根据that akka issue，每条消息，即使非常小，也可能以 Streamed 结束。如果你想打印所有文本消息，一个更好的 actor 实现是：

object Rec extends Actor {
  override def receive: Receive = {
    case TextMessage.Strict(text)             ⇒ println(s"Received signal $text")
    case TextMessage.Streamed(textStream)     ⇒ textStream.runFold("")(_ + _).foreach(msg => println(s"Received streamed signal: $msg"))
  }
}

请在 my github 上找到一个工作项目。

Answer 2

我找到了解决方案：我使用的服务器是运行在 IPv6 上（作为 ::1），但 akka-http 将本地主机视为 127.0.0.1 并忽略 ::1。我不得不重写服务器以强制它使用 IPv4 并且它起作用了。

Akka-http：连接到本地主机上的 websocket

Akka-http: connect to websocket on localhost

scala

websocket

akka-stream

akka-http