Question

I’m new to RMI technology and facing below issue.

We have Multiple Devices of same type connected to Local System, where on each device RMI service is running on different ports.

When we are trying to connect single device to local system through RMI its working fine.
When we try to connect second device to local system, we are getting error as below –

Could you please help us to resolve below issue?

Thanks in advance.

    java.rmi.ConnectException: Connection refused to host: 127.0.0.1; nested exception is: 
        java.net.ConnectException: Connection refused: connect
        at sun.rmi.transport.tcp.TCPEndpoint.newSocket(TCPEndpoint.java:601)
        at sun.rmi.transport.tcp.TCPChannel.createConnection(TCPChannel.java:198)
        at sun.rmi.transport.tcp.TCPChannel.newConnection(TCPChannel.java:184)
        at sun.rmi.server.UnicastRef.newCall(UnicastRef.java:322)
        at sun.rmi.registry.RegistryImpl_Stub.rebind(Unknown Source)
        at java.rmi.Naming.rebind(Naming.java:160)
        at com.rmi.server.RMIServer.exportAndBindObject(Unknown Source)

Demo.java

    this.myRMIServer = new RMIServer(this.RMIServerPort,this.RMIClientPort, new RMISocketFactory());
    this.helloWorld = new HelloWorld();
    this.myRMIServer.exportObject(this.helloWorld);
    this.myRMIServer.exportAndBindObject(this.rmiServiceName, this.helloWorld);

RMIServer.java

    public RMIServer(int port, int rmiPort, java.rmi.server.RMISocketFactory sf)
            throws RemoteException {
        this.sf = sf;
        this.rmiPort = rmiPort;
        this.regPort = port;
        synchronized (this) {
            if (registry == null)
                registry = LocateRegistry.createRegistry(port);
        }
    }

    public void exportAndBindObject(String name, RemoteObject ro)
            throws RemoteException, MalformedURLException {
        exportObject(ro);
        String url = "//127.0.0.1:" + this.regPort + "/" + name;
        Naming.rebind(url, ro);
    }

Answer 1

You are creating the Registry on port but binding to it on regPort, where it isn’t found.

I don’t know what the purpose of this.RMIClientPort can possibly be. I would get rid of it. RMI servers have no business thinking about client ports.

Also you’re exporting the HelloWorld object twice: once in Demo.java where you call exportObject(), and once in RMIServer.exportAndBindObject() where you call exportObject() again. So one of those operations must have failed, or else it didn’t export anything. So there is something wrong in your exportObject() method.