[ros-users] rosjava xmlRpcPort issue

Hi Friends,
I am new to Ros an rosjava and tying to do something on my PC.
I am not sure its correct or not.

I am using rosjava on my Linux (ubuntu 10.4).
Currently I am trying to run rosjava alone. and trying to use Talker and
Listener example available in source.

I am starting Ros core and talker and listener by following commands

RosCore --
rosCore = new RosCore(11311);
nodeRunner = NodeRunner.createDefault();
nodeRunner.run(rosCore, Lists.newArrayList("RosCore", "__master:=
http://localhost:11311"));

Talker
nodeRunner.run(new Talker(),Lists.newArrayList("talker", "__ip:=127.0.0.1",
"__master:=http://localhost:11311"));

Listener
nodeRunner.run(new Listener(),Lists.newArrayList("listener",
"__ip:=127.0.0.1", "__master:=http://localhost:11311"));

Publisher and subscriber are not able to communicate. AndI am trying to
understand why..
I found that value of xmlRpcPort is 0 and not changed anywhere.

Am I doing right thing by running rosjava alone?
Is xmlRpcPort port need to set? whats is it for? I suppose it might be for
remote communication with RcpCore (or MasterServer)

in my case rosroot and ros package paths are empty...is that ok?

Thanks and Regards
Abhishek Verma