Problem running RMI

melida · September 23rd, 2003, 09:33 AM

Hello,

I am experimenting with Java RMI. I know RMI is a part of J2SE and not J2EE but I have this example from "Professional Java Server Programming J2EE 1.3 Edition" and you don't have any other appropriate thread for it.

After I have bought "Professional Java
Server Programming J2EE 1.3 Edition" from WROX I try to run the first
RMI-example. But something is going wrong:

1) if I try to run rmiregistry with appropriate policy-file, I get buffer
   overflow exception from RegisterIt - class (after a very long time)
   while registring my server-class.

2) in some faq - lists I found a work-around with
   sun.rmi.registry.RegistryImpl ("java
   -Djava.security.policy=registerit.policy
   sun.rmi.registry.RegistryImpl").

   So I first create server class. Next I create server stub
   (now they are matching). Then I create client class and registration class.
   Now I start registry and register my server-class, but if
   I try to connect it from my client class, I still get
   "java.rmi.UnmarshalException: invalid method hash".

   I know this exception appears if my stub is not matching my remote server
   class. But it is not possible because I always generate my stub after
   creating server class so they must be synchronized.

3) When I try out Activatable example on my system and try to registry my
   activatable server class I get connection refused exception (rmid is
   running). I can only register my server class if
   sun.rmi.registry.RegistryImpl is running too. But then I get invalid method
   hash when I was trying to run my client class.

Has anyone an idea what is going wrong?
Why rmiregistry does not work on my system?
Why rmid does not work?

I am wondering if I have to set some environmental variables because of the
fact that nothing concerned rmi is running on my system properly.

I am working with Java 1.4.1 and BlackdownJava2-1.4.1.

Lydia

   Here are my files (not for activatable example):

   Server-Interface

Code:

public interface HelloInterface extends java.rmi.Remote
{
    // This method is called by remote clients and is implemented
    // by remote object
    public String hello() throws java.rmi.RemoteException;
}

Server-Class

Code:

import java.io.*;
import java.rmi.*;
import java.rmi.server.*;

public class HelloServer extends UnicastRemoteObject
                         implements HelloInterface
{
    public HelloServer() throws RemoteException
    {
        super();
    }

    public String hello() throws RemoteException
    {
        return "Hello World";
    }
}

Register-Class

Code:

import java.rmi.*;

public class RegisterIt
{
    public static void main(String args[])
    {
        try
        {
        HelloServer obj = new HelloServer();
        System.err.println("Object instantiated : " + obj);
        System.err.println("rebinding HelloServer...");
        Naming.rebind("/HelloServer", obj);
        System.err.println("HelloServer bound in registry");
        }
        catch (Exception e)
        {
        e.printStackTrace();
        }
    }
}

Client-Class

Code:

import java.rmi.*;

public class HelloClient
{
    public static void main(String args[])
    {
        if (System.getSecurityManager() == null)
        {
        System.setSecurityManager(new RMISecurityManager());
        }

        try
        {
            HelloInterface obj = (HelloInterface) Naming.lookup("/HelloServer");
        String message = obj.hello();
        System.err.println(message);

        }
        catch (Exception e)
        {
        e.printStackTrace();
        }
    }
}