Error when calling remote method

Question

I'm trying to call a fibonacci method on a remote server using RMI but when I try to invoke the method on the client side by giving the method an integer value, I get these errors:

java.rmi.ServerException: RemoteException occurred in server thread; nested exception is:
    java.rmi.UnmarshalException: unrecognized method hash: method not supported by remote object
    at sun.rmi.server.UnicastServerRef.dispatch(Unknown Source)
    at sun.rmi.transport.Transport$1.run(Unknown Source)
    at sun.rmi.transport.Transport$1.run(Unknown Source)
    at java.security.AccessController.doPrivileged(Native Method)
    at sun.rmi.transport.Transport.serviceCall(Unknown Source)
    at sun.rmi.transport.tcp.TCPTransport.handleMessages(Unknown Source)
    at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run0(Unknown Source)
    at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run(Unknown Source)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
    at java.lang.Thread.run(Unknown Source)
    at sun.rmi.transport.StreamRemoteCall.exceptionReceivedFromServer(Unknown Source)
    at sun.rmi.transport.StreamRemoteCall.executeCall(Unknown Source)
    at sun.rmi.server.UnicastRef.invoke(Unknown Source)
    at java.rmi.server.RemoteObjectInvocationHandler.invokeRemoteMethod(Unknown Source)
    at java.rmi.server.RemoteObjectInvocationHandler.invoke(Unknown Source)
    at com.sun.proxy.$Proxy0.fibonacciArrayTest(Unknown Source)
    at ie.gmit.FibonacciClient.main(FibonacciClient.java:37)

Does anyone have any idea where I have gone wrong with this implementation?

This is the client side of the RMI application:

      //get user input 
      Scanner user_input = new Scanner(System.in);
      String fibMaxNum;

      System.out.println("Enter the max fibonacci number: ");
      fibMaxNum = user_input.next();


      int fibMax = Integer.parseInt(fibMaxNum);

     //Get Fibonacci array.
     int[] sequence = power_proxy.fibonacciArrayTest(fibMax);
     for (int value : sequence) {
        System.out.println(value);
     }

And this is the implementation on the server side, I also get an error here The return type is incompatible with IPower.fibonacciArrayTest(int).I gather from this that I'm not specifying the correct return type in the Ipower interface, but how can I correct the signatures to fix this? Should I Change the method in Ipower to :

   public int[] fibonacciArrayTest(int n) {

        int a = 0;
        int b = 1;
        int[] sequence = new int[n];

        // Fill array with Fibonacci values.
        for (int i = 0; i < n; i++) {
            sequence[i] = a;

            int temp = a;
            a = b;
            b = temp + b;
        }
        return sequence;
        }

The interface:

public interface IPower extends Remote{

     //Declare available methods and must throw RemoteException 
      int[] fibonacciArrayTest(int fibMax) throws RemoteException;

}

Answer 1

You've changed your remote method signature after deployment.

Clean and rebuild and redeploy to both client and server, not forgetting to restart the Registry too.