How do I get my RMI Proxy to work

Question

Hi there
I have created a nice RMI callback server and client - that works fine.
The server and client has to be able to run on seperate LAN's - LAN A and LAN B. The server is on LAN A and the client is on LAN B - furthermore I have a PC with connected to both LAN A and B on two different network adapters.
In order to make the server and client communicate - I have made a RMI proxy that implements both the server and client interface. Normally you specify that the RMI server should use LAN A or B by specifying the java.rmi.server.hostname property.
The problem is that the proxy only works on the LAN matching the specified java.rmi.server.hostname property. It seems the client also depends on the java.rmi.server.hostname property - probably because I use a callback implementation
Any suggestions to how I solve this ?

Answer 1

A url in Bug# 4880793 led me to a solution proposed by Peter Jones - JavaSoft East.
Well for some reason the java.rmi.server.hostname affects how all sockets are created by the RMI factories.
In order to control which adapter to use manually you will have to your create your own socket factories:
import java.io.*;
import java.net.*;
import java.rmi.server.*;
import javax.net.*;
public class MyClientSocketFactory implements RMIClientSocketFactory, Serializable {
private final String aCorrectHost;
public MyClientSocketFactory(String host) {
aCorrectHost = host;
public Socket createSocket(String host, int port) throws IOException {
return new Socket(aCorrectHost, port);
public boolean equals(Object obj) {
if (obj instanceof MyClientSocketFactory) {
MyClientSocketFactory other = (MyClientSocketFactory) obj;
return aCorrectHost == other.aCorrectHost;
return false;
public int hashCode() {
return aCorrectHost.hashCode();
import java.io.*;
import java.net.*;
import java.rmi.server.*;
public class MyServerSocketFactory implements RMIServerSocketFactory, Serializable {
public ServerSocket createServerSocket(int port) throws IOException {
return new ServerSocket(port);
public boolean equals(Object obj) {
if (obj instanceof MyServerSocketFactory) {
return true;
return false;
public int hashCode() {
return "MyServerSocketFactory".hashCode();
I have not got the time to be more specific - so I hope this will be help enough.
Kind regards
hjembaek