如何在一个程序关闭并重新启动而另一个程序保持运行在Java后恢复RMI通信？

Question

所以我目前有很多代码，很难将它们全部分解成一个 SSCCE，但如果有必要，我可能稍后会尝试这样做。

无论如何，这里是要点：我有两个进程通过 RMI 进行通信。有用。但是，如果主机进程 (JobViewer) 退出通信，我希望能够继续，然后 returns 全部在客户端进程 (Job) 的生命周期中。

目前，每次作业启动时，我都会将绑定名称保存到文件中，并且 JobViewer 在启动时打开该文件。效果很好，正确的绑定名称有效。但是，每次我尝试恢复与 JobViewer 重新启动时实际上仍然是运行的作业的通信时，我都会收到 NotBoundException。

我的 JobViewer 使用以下方法实现了一个扩展 Remote 的接口：

public void registerClient(String bindedName, JobStateSummary jobSummary) throws RemoteException, NotBoundException;
public void giveJobStateSummary(JobStateSummary jobSummary) throws RemoteException;
public void signalEndOfClient(JobStateSummary jobSummary) throws RemoteException;

我的 Job 还实现了一个不同的接口，它使用以下方法扩展 Remote：

public JobStateSummary getJobStateSummary() throws RemoteException;
public void killRemoteJob() throws RemoteException;
public void stopRemoteJob() throws RemoteException;
public void resumeRemoteJob() throws RemoteException;

我该如何实现？这是我当前的一些初始化 RMI 的代码，如果有帮助的话...

JobViewer 端：

private Registry _registry;
// Set up RMI
_registry = LocateRegistry.createRegistry(2002);
_registry.rebind("JOBVIEWER_SERVER", this);

工作方面：

private NiceRemoteJobMonitor _server;

Registry registry = LocateRegistry.getRegistry(hostName, port);
registry.rebind(_bindedClientName, this);
Remote remoteServer = registry.lookup(masterName);

_server = (NiceRemoteJobMonitor)remoteServer;
_server.registerClient(_bindedClientName, _jobStateSummary);

Answer 1

I get a NotBoundException every time I try to resume communication with a Job that I know for fact is still running when the JobViewer restarts.

这只有在 JobViewer 启动时没有重新绑定自身的情况下才会发生。当您使用陈旧的存根时，通常会得到 NoSuchObjectException，即远程对象已退出的存根。在这种情况下，您应该重新获取存根，即重做 lookup().

为什么客户端将自己绑定到注册表？如果要注册回调，只需将 this 传递给 registerClient() 方法而不是绑定名称，并相应地调整其签名（使用客户端的远程接口作为参数类型）。无需让服务器查找客户端注册表。根本不需要客户端注册表。

Answer 2

我的解决方案是让 Job 每隔一段时间 ping JobViewer：

  while (true) {

    try {

      _server.ping();
      // If control reaches here we were able to successfully ping the job monitor.

    } catch (Exception e) {

      System.out.println("Job lost contact with the job monitor at " + new Date().toString() + " ...");

      // If control reaches we were unable to ping the job monitor.  Now we will loop until it presumably comes back to life.
      boolean foundServer = false;
      while (!foundServer) {

        try {

          // Attempt to register again.
          Registry registry = LocateRegistry.getRegistry(_hostName, _port);
          registry.rebind(_bindedClientName, NiceSupervisor.this);
          Remote remoteServer = registry.lookup(_masterName);
          _server = (NiceRemoteJobMonitor)remoteServer;
          _server.registerClient(_bindedClientName, _jobStateSummary);

          // Ping the server for good measure.
          _server.ping();

          System.out.println("Job reconnected with the job monitor at " + new Date().toString() + " ...");

          // If control reaches here we were able to reconnect to the job monitor and ping it again.
          foundServer = true;

        } catch (Exception x) {

          System.out.println("Job still cannot contact the job monitor at " + new Date().toString() + " ...");

        }

       // Sleep for 1 minute before we try to locate the registry again.
        try {
          Thread.currentThread().sleep(PING_WAIT_TIME);
        } catch (InterruptedException x) {

        }

     } // End of endless loop until we find the server again.

   }

    // Sleep for 1 minute after we ping the server before we try again.
    try {
      Thread.currentThread().sleep(PING_WAIT_TIME);
    } catch (InterruptedException e) {

    }

  }  // End of endless loop that we never exit.

如何在一个程序关闭并重新启动而另一个程序保持运行在Java后恢复RMI通信？

How to resume RMI communication after a program shuts down and restarts while the other remains running in Java?

java

rmi