how to run ros on raspberry-pi and another machine

edit

I want to run a talker node on my ubuntu and subscriber "listener node " on raspberry pi on raspbian I already set the ROS_MASTER_URI to the ip of my raspberry pi and nodes are run correctly but it doesn't subscribe anything :\

this is my roswtf output

Loaded plugin tf.tfwtf
No package or stack in context
================================================================================
Static checks summary:

Found 1 error(s).

ERROR Not all paths in PYTHONPATH [/home/ubuntu/catkin_ws/devel/lib/python2.7/dist-packages:/opt/ros/indigo/lib/python2.7/dist-packages] point to a directory: 
 * /home/ubuntu/catkin_ws/devel/lib/python2.7/dist-packages

================================================================================
Beginning tests of your ROS graph. These may take awhile...
analyzing graph...
... done analyzing graph
running graph rules...
ERROR: Unknown host [raspberrypi] for node [/rosout]
... done running graph rules

Online checks summary:

Found 1 warning(s).
Warnings are things that may be just fine, but are sometimes at fault

WARNING The following node subscriptions are unconnected:
 * /rosout:
   * /rosout


Found 2 error(s).

ERROR Could not contact the following nodes:
 * /rosout

ERROR Errors connecting to the following services:
 * service [/rosout/get_loggers] appears to be malfunctioning: Unable to communicate with service [/rosout/get_loggers], address [rosrpc://raspberrypi:33201]
 * service [/rosout/set_logger_level] appears to be malfunctioning: Unable to communicate with service [/rosout/set_logger_level], address [rosrpc://raspberrypi:33201]