Re: Problem with RMI Creating an extra port

On Fri, Sep 26, 2008 at 05:46:31AM -0600, Greg Luck wrote:
> Following is a simple example that sets a port for
> UnicastRemoteObject and for the RMI Registry.
> 
> I am having this problem with ehcache RMI replication (which I
> maintain) as reported my a user trying to get it to work through a
> firewall.
> 
> The problem is that when Naming.rebind() is called, a new random
> port gets listened on.
> 
> I do not understand why this is happening or how I can stop it from
> happening. This example follows the ways of controlling port usage
> as described in this list, from what I have read.
> 
> package net.sf.ehcache.distribution;
> 
> import java.rmi.registry.LocateRegistry;
> import java.rmi.server.*;
> import java.rmi.*;
> 
> public class RMIPortUsage extends UnicastRemoteObject {
> 
>     private static RMIPortUsage rmi;
> 
>     protected RMIPortUsage(int port) throws RemoteException {
>         super(port);
>     }
> 
>     public static void main(String[] args) throws Exception {
>         int port = 10001;
>         String service = "rmi://127.0.0.1" + ':' + port + '/' +
>                 "Pips";
>         rmi = new RMIPortUsage(port);
>         LocateRegistry.createRegistry(port);
> 
>         //Ports being listend to: 
>         //Sep 26 21:29:52 Greg-Lucks-Laptop Firewall[57]: java is listening from ::ffff:0.0.0.0:10001 uid = 501 proto=6
>         Naming.rebind(service, rmi);
> 
> 
>         //Ports being listened to:
>         //Sep 26 21:29:52 Greg-Lucks-Laptop Firewall[57]: java is listening from ::ffff:0.0.0.0:10001 uid = 501 proto=6
>         //Sep 26 21:30:36 Greg-Lucks-Laptop Firewall[57]: java is listening from ::ffff:127.0.0.1:57915 uid = 501 proto=6

This code indeed should only cause RMI to listen on one port (10001),
and that is in fact the case when I run it, with various JDK versions
on Solaris 10-- what JDK version and OS are you using?

The Naming.rebind invocation should not cause RMI to create any new
passive/listening sockets--- it would, however, cause the first
active/connecting socket to be created, to port 10001, for the RMI
call to the registry.  Are you certain that the port 57915 (in the
above-described case) was not just the peer port on the client side of
that connection?

-- Peter

===========================================================================
To unsubscribe, send email to [email protected] and include in the body
of the message "signoff RMI-USERS".  For general help, send email to
[email protected] and include in the body of the message "help".

For a list of frequently asked RMI questions please refer to:
http://java.sun.com/j2se/1.3/docs/guide/rmi/faq.html

To view past RMI-USERS postings, please see:
http://archives.java.sun.com/archives/rmi-users.html