使用 Java 的 Akka 远程路由

Question

我正在尝试实现一个基本的广播路由器，其中路由位于远程机器上。

代码如下：

localApp.conf

akka {

    log-dead-letters = 10
    log-dead-letters-during-shutdown = off

    actor {
        provider = "akka.remote.RemoteActorRefProvider"
        serialize-messages = on

        serializers {
            java = "akka.serialization.JavaSerializer"
        }

        serialization-bindings {
            "java.lang.String" = java
            "test.akkaLocal.LocalWrapper" = java
        }

        deployment {
            /LocalMaster/broadcastRouter {
                router = "broadcast"
                nr-of-instances = 1
                target {
                    nodes = ["akka.tcp://RemoteApp@127.0.0.1:10175"]
                }
            }
        }
    }
    remote {
        enabled-transports = ["akka.remote.netty.tcp"]
        netty {
            tcp {
                hostname = "127.0.0.1"
                port = 10174
            }
        }
    }
}

LocalApp.java

public class LocalApp
{
    public static void main(String[] args)
    {
        LocalApp app = new LocalApp();
        app.executeLocal();
    }

    private void executeLocal() {
        ActorSystem system = ActorSystem.create("LocalApp", ConfigFactory.load("localApp"));
        final ActorRef master = system.actorOf(Props.create(LocalMaster.class), "LocalMaster");
        master.tell(new LocalWrapper.Execute(), ActorRef.noSender());
    }

    public static class LocalMaster extends UntypedActor {

        @Override
        public void onReceive(Object message) throws Exception {
            if (message instanceof LocalWrapper.Execute) {

                ActorSelection remoteActor =
                        getContext().actorSelection("akka.tcp://RemoteApp@127.0.0.1:10175/user/RemoteMaster");

                ActorRef remoteRouter = getContext().actorOf(
                        Props.create(RemoteActor.class).withRouter(new FromConfig()), "broadcastRouter");

                String msg = "Hello";
                // remoteActor.tell(msg, getSelf());
                remoteRouter.tell(msg, getSelf());
            } else if (message instanceof String) {
                String response = (String) message;
                System.out.println(response);
            }
        }

    }

    public static class RemoteActor extends UntypedActor {
        @Override
        public void onReceive(Object message) throws Exception {
            if (message instanceof String) {
                String msg = (String) message;
                System.out.println(msg);

                String resp = "World";
                getSender().tell(resp, getSelf());

            }
        }
    }
}

在remoteApp.conf中，端口为10175

RemoteApp.java

public class RemoteApp
{
    public static void main(String[] args)
    {
        RemoteApp app = new RemoteApp();
        app.executeRemote();
    }

    private void executeRemote() {
        ActorSystem system = ActorSystem.create("RemoteApp", ConfigFactory.load("remoteApp"));
        system.actorOf(Props.create(RemoteMaster.class), "RemoteMaster");
    }

    public static class RemoteMaster extends UntypedActor {

        @Override
        public void onReceive(Object message) throws Exception {
            if (message instanceof String) {
                String msg = (String) message;
                System.out.println(msg);
                String response = "World";
                getSender().tell(response, getSelf());
            }
        }
    }

}

现在我无法理解远程路由的概念。它是在远程机器上部署本地actor然后向它们发送消息，还是连接到远程机器上的远程actor然后向它们发送消息？

使用我的代码，我可以向远程机器发送简单的消息（使用演员选择） LocalApp 中的 remoteActor.tell(msg, getSelf()) （注释代码）发送和接收消息并且没有给出任何错误。

但是当我使用本地 Actor 创建路由器时，出现死信错误。

[INFO] [02/04/2014 16:34:58.408] [RemoteApp-akka.actor.default-dispatcher-4] [akka://RemoteApp/system/endpointManager/reliableEndpointWriter-akka.tcp%3A%2F%2FLocalApp%40127.0.0.1%3A10174-0/endpointWriter/endpointReader-akka.tcp%3A%2F%2FLocalApp%40127.0.0.1%3A10174-0] 
Message [akka.remote.transport.AssociationHandle$InboundPayload] from Actor[akka://RemoteApp/deadLetters] to Actor[akka://RemoteApp/system/endpointManager/reliableEndpointWriter-akka.tcp%3A%2F%2FLocalApp%40127.0.0.1%3A10174-0/endpointWriter/endpointReader-akka.tcp%3A%2F%2FLocalApp%40127.0.0.1%3A10174-0#-288427524] was not delivered.
[1] dead letters encountered. This logging can be turned off or adjusted with configuration settings 'akka.log-dead-letters' and 'akka.log-dead-letters-during-shutdown'.

谁能告诉我我做错了什么？

---------更新----------

我发现了问题。远程和本地类在不同的项目中。在本地和远程项目之间的基本通信过程中，String 是传输对象的类型，这就是它成功的原因。有没有办法在两个不同的项目之间传输自定义类的对象？我尝试实现 Serializable 并将其添加到 conf 文件中，但它没有任何区别

Answer 1

默认情况下，akka 将为自定义消息类使用 java 序列化。如果类定义在系统两侧（发送端和接收端）都可用（即在类路径中），那么您应该能够将其用于远程通信。我的建议是有一个 jar 文件来表示系统两侧的类路径中可用的消息类。

Akka 还允许您为不同的消息类类型使用不同的序列化程序，因此您不会被 java 序列化所困，但如果您愿意，我建议先让它以这种方式工作，然后再尝试其他序列化程序。