RMI server keeps running in MAC OSX platform but not in Windows XP platform

[Ad Tan]

Hi all, I was trying out the same set of RMI server codes on MAC OSX and Windows XP platform, both using Java 6.

    private static final int RMI_PORT = Registry.REGISTRY_PORT;

    public static void main(String[] args) {
        try {
            ServiceRemote service = new ServiceRemoteImpl();
            Registry registry = LocateRegistry.createRegistry(RMI_PORT);
            registry.rebind("Business", UnicastRemoteObject.exportObject(service, RMI_PORT));

            System.out.println("Server started!");
        } catch (Exception e) {
            System.out.println("Error occurred at server  " + e.getMessage());
        }
    }

Strangely, in MAC OSX, the server keeps running (in terminal), whereas in Windows, the server starts and stops (in command prompt).

After some googling, it seems that in some cases, the remote object was GCed very soon, and hence the server stops.

Moving the 'service' declaration out of main method (as a static reference) fixed this problem. However, I'm not sure if this is the correct way of solving this problem. Anyone has any comment on this approach?

[Ad Tan]

Just found out if my remote object extends UnicastRemoteObject, this would not be a problem. Not too sure why

[Jari Timonen]

Extend UnicastRemoteObject or use exportObject. Not both

[Roel De Nijs]

Hi Ad,

Like Jari also mentioned it's not necessary to do both: extend from UnicastRemoteObject and use exportObject. I decided to use the exportObject-method (and make it possible in future to let my service implementation class extend from some generic service class).

Ad Tan wrote:Moving the 'service' declaration out of main method (as a static reference) fixed this problem. However, I'm not sure if this is the correct way of solving this problem. Anyone has any comment on this approach?

I did that too, but too solve another issue I experienced. Take a look here for more details.

Kind regards,
Roel

[Roberto Perillo]

Howdy, Ad!

Champion, try the following:

    private static final int RMI_PORT = Registry.REGISTRY_PORT;

    public static void main(String[] args) {
        try {
            ServiceRemote service = (ServiceRemote) UnicastRemoteObject.exportObject(new ServiceRemoteImpl(), 0);
            Registry registry = LocateRegistry.createRegistry(RMI_PORT);
            registry.rebind("Business", service);
            System.out.println("Server started!");
        } catch (Exception e) {
            System.out.println("Error occurred at server  " + e.getMessage());
        }
    }

When you call UnicastRemoteObject.exportObject(), you should pass 0 as argument. Maybe that's the problem.

[Ad Tan]

Jari Timonen wrote:Extend UnicastRemoteObject or use exportObject. Not both

Oooh, sorry wasn't too clear in my posting, in my findings, the 2 methods can be used to launch the server. However, the exportObject method would not allow the server to continue running (the Thread will finish running) unless I put the remote instance in a static variable.

I tried Roberto's suggestion... but no success either.