RMI binding to SAME port but DIFFERENT IP address on SAME host

[Alexander N. Spitzer]

If I have a machine with 3 virtual IP addresses (192.168.1.[5-7]), how
can I start 3 instances of the same RMI application (each started with
different properties/configs), each listening on the port 1234, but each
instance binds to a different ip address.

that is to say:
instance #1 binds to 192.168.1.5/port 1234
instance #2 binds to 192.168.1.6/port 1234
instance #3 binds to 192.168.1.7/port 1234

I guess I am looking for something like:
Registry registry = LocateRegistry. createRegistry( <IPADDR>,<PORT> );

I tried
System.setPrope rty("java.rmi.s erver.hostname" ,"<IPADDR>") ;
but had no luck
current code looks something like this:

/******* server side *********/
System.getPrope rties().setProp erty("java.rmi. server.hostname ",serverip) ;
Registry registry = LocateRegistry. createRegistry( serverport);
registry.rebind ("RMITest", this);

//serverip is the IP to bind to... server port is port 1234

/******* client side **********/
Registry registry=Locate Registry.getReg istry(serverip, serverport);
RMITestInterfac e rmit=(RMITestIn terface)(regist ry.lookup("RMIT est"));
rmit.dosomethin gcool();
second instance (even though serverip is different) complains
java.rmi.server .ExportExceptio n: Port already in use:1234; nested
exception is: java.net.BindEx ception: Address already in use

These have to be seperate instances of the application for each
customer... I know that it is possible to run them on different ports,
but this is really not acceptable in a large clustered environment. this
would become a complete nightmare very quickly.
what am I missing?!?! I have googled high and low, and looked through
all my java books, but see no mention of such a scenario! anyone?

TIA!

-alex

[Alex Molochnikov]

"Alexander N. Spitzer" <al**@spitzer.N OSPAMPLEASE.org > wrote in message
news:mN******** ********@nwrdny 03.gnilink.net. ..
[snipped]

I guess I am looking for something like:
Registry registry = LocateRegistry. createRegistry( <IPADDR>,<PORT> );

There is no method in LocateRegistry with this signature. You can create a
Registry object bound to a specific IP address using this form of the
method:

public static Registry createRegistry( int port, RMIClientSocket Factory csf,
RMIServerSocket Factory ssf) throws RemoteException

You will have to provide a class that implements the RMIServerSocket Factory
interface (the RMIClientSocket Factory parm can be null); this class will
create a ServerSocket that you will have to bind to the desired IP address.
Here is an example:

import java.rmi.server .*;
import java.io.*;
import java.net.*;
public class AnchorSocketFac tory extends RMISocketFactor y implements
Serializable
{
private InetAddress ipInterface = null;
public AnchorSocketFac tory() {}
public AnchorSocketFac tory(InetAddres s ipInterface)
{
this.ipInterfac e = ipInterface;
}
public ServerSocket createServerSoc ket(int port)
{
ServerSocket serverSocket = null;
try
{
serverSocket = new ServerSocket(po rt, 50, ipInterface);
}
catch (Exception e)
{
System.out.prin tln(e);
}
return (serverSocket);
}
public Socket createSocket(St ring dummy, int port) throws IOException
{
return (new Socket(ipInterf ace, port));
}
public boolean equals(Object that)
{
return (that != null && that.getClass() == this.getClass() );
}
}

In your code do this:

AnchorSocketFac tory sf = new AnchorSocketFac tory(<your InetAddress>);
LocateRegistry. createRegistry( port, null, sf);

HTH

Alex Molochnikov
Gestalt Corporation
www.gestalt.com

[Sam]

"Alexander N. Spitzer" <al**@spitzer.N OSPAMPLEASE.org > wrote in message news:<mN******* *********@nwrdn y03.gnilink.net >...

If I have a machine with 3 virtual IP addresses (192.168.1.[5-7]), how
can I start 3 instances of the same RMI application (each started with
different properties/configs), each listening on the port 1234, but each
instance binds to a different ip address.

that is to say:
instance #1 binds to 192.168.1.5/port 1234
instance #2 binds to 192.168.1.6/port 1234
instance #3 binds to 192.168.1.7/port 1234

I guess I am looking for something like:
Registry registry = LocateRegistry. createRegistry( <IPADDR>,<PORT> );

I tried
System.setPrope rty("java.rmi.s erver.hostname" ,"<IPADDR>") ;
but had no luck
current code looks something like this:

/******* server side *********/
System.getPrope rties().setProp erty("java.rmi. server.hostname ",serverip) ;
Registry registry = LocateRegistry. createRegistry( serverport);
registry.rebind ("RMITest", this);

//serverip is the IP to bind to... server port is port 1234

/******* client side **********/
Registry registry=Locate Registry.getReg istry(serverip, serverport);
RMITestInterfac e rmit=(RMITestIn terface)(regist ry.lookup("RMIT est"));
rmit.dosomethin gcool();
second instance (even though serverip is different) complains
java.rmi.server .ExportExceptio n: Port already in use:1234; nested
exception is: java.net.BindEx ception: Address already in use

These have to be seperate instances of the application for each
customer... I know that it is possible to run them on different ports,
but this is really not acceptable in a large clustered environment. this
would become a complete nightmare very quickly.
what am I missing?!?! I have googled high and low, and looked through
all my java books, but see no mention of such a scenario! anyone?

TIA!

-alex

Alex,

I doubt an end host keeps multiple ports for each active ip address.
Data from a nic card is passed up the protocol stack, and the source
ip address has been discarded by the time it reaches the port.

You might try a single RMI server listening on a single port, passing
data to a given instance of a jvm based on customer id.

Sam90

[Alexander N. Spitzer]

> Alex,

I doubt an end host keeps multiple ports for each active ip address.
Data from a nic card is passed up the protocol stack, and the source
ip address has been discarded by the time it reaches the port.

You might try a single RMI server listening on a single port, passing
data to a given instance of a jvm based on customer id.

Sam90

Sam, in an ASP environment, it is a requirement to have seperate
instances for each client.

Alex Molochnikov gave me the answer I was looking for, which was:

There is no method in LocateRegistry with this signature. You can create
a Registry object bound to a specific IP address using this form of the
method:

public static Registry createRegistry( int port, RMIClientSocket Factory
csf,RMIServerSo cketFactory ssf) throws RemoteException

Thanks Alex M. et al.!

[Esmond Pitt]

Sam wrote:

I doubt an end host keeps multiple ports for each active ip address.
Data from a nic card is passed up the protocol stack, and the source
ip address has been discarded by the time it reaches the port.

Sam, none of this guesswork is true.

[Sam]

"Alexander N. Spitzer" <al**@spitzer.N OSPAMPLEASE.org > wrote in message news:<41******* *******@spitzer .NOSPAMPLEASE.o rg>...

Alex,

I doubt an end host keeps multiple ports for each active ip address.
Data from a nic card is passed up the protocol stack, and the source
ip address has been discarded by the time it reaches the port.

You might try a single RMI server listening on a single port, passing
data to a given instance of a jvm based on customer id.

Sam90

Sam, in an ASP environment, it is a requirement to have seperate
instances for each client.
That actually is what I was proposing - but that's a moot point, since
you got Alex's correct answer.

Alex Molochnikov gave me the answer I was looking for, which was:
There is no method in LocateRegistry with this signature. You can create
a Registry object bound to a specific IP address using this form of the
method:

public static Registry createRegistry( int port, RMIClientSocket Factory
csf,RMIServerSo cketFactory ssf) throws RemoteException
My bad - I did some speculation which I didn't check, and now see what
happened. Alex's answer didn't make to Google by the time I made my
post

Thanks Alex M. et al.!

Agreed.

Regards,
Sam90

[Sam]

Esmond Pitt <es*********@no t.bigpond.com> wrote in message news:<Dt******* ************@ne ws-server.bigpond. net.au>...

Sam wrote:

I doubt an end host keeps multiple ports for each active ip address.
Data from a nic card is passed up the protocol stack, and the source
ip address has been discarded by the time it reaches the port.

Sam, none of this guesswork is true.

It isn't? How so?

Regards,
Sam90

[Esmond Pitt]

Sam wrote:

I doubt an end host keeps multiple ports for each active ip address.
Data from a nic card is passed up the protocol stack, and the source
ip address has been discarded by the time it reaches the port.

Sam, none of this guesswork is true.

It isn't? How so?

Because what the OP described is perfectly possible, despite your doubts
and speculations. See ServerSocket(po rt,backlog,bind Address). If you
don't know the answer please don't guess, it only confuses others.

[Sam]

Esmond Pitt <es*********@no t.bigpond.com> wrote in message news:<8A******* ************@ne ws-server.bigpond. net.au>...

Sam wrote:

I doubt an end host keeps multiple ports for each active ip address.
Data from a nic card is passed up the protocol stack, and the source
ip address has been discarded by the time it reaches the port.

Sam, none of this guesswork is true.

It isn't? How so?

Because what the OP described is perfectly possible, despite your doubts
and speculations.

I agree my speculation was incorrect, and I admit it and I'm not happy
about it. However, I did qualify it, that is I didn't say "this is the
gospel truth" or anything like that. I said "I doubt it", which
liberally translated means, "I'm shooting from the hip, beware".
Besides, nothing I said was actually false. I just want to clarify
that. Specifically, an end host doesn't track mutliple ports per ip -
does it? When data is passed up the protocol stack, the IP address is
discarded by the time it reaches
See ServerSocket(po rt,backlog,bind Address).
I have, and I'm pretty sure I figured out where I went wrong.
If you
don't know the answer please don't guess, it only confuses others.

I did get sloppy, and I admit it. Oh well, no harm done, luckily
someone came along with the correct answer, actually even before I
posted my poor one. I'll be more careful next time.

Regards,
Sam90

[Esmond Pitt]

Sam

I don't really know what you mean by 'tracks multiple ports per IP',
which TCP certainly does otherwise nothing would work at all. Maybe you
mean 'multiple IP addresses per port'? in which case the answer is
certainly 'yes' as well, hence the ServerSocket constructor I referred
you to. The local IP address by which incoming data came in is not
reliable due to the 'weak end system model' described in the RFC, maybe
this is what you are referring to, but the IP address to which the
reading socket is bound is always available via Socket.getLocal Address().

EJP