Reconnect to ROSCORE

edit

I modified the talker.py to
(1) Use get_system_state to test the existence of roscore. Though I am wondering if there is a formal way to test the existence of roscore.
(2) when disconnected, restart from scratch (init_node, publish ...)

import roslib; roslib.load_manifest('rospy_tutorials')

import rospy
from std_msgs.msg import String

def talker():
    pub = rospy.Publisher('chatter', String)
    rospy.init_node('talker', anonymous=True, log_level=rospy.DEBUG)
    r = rospy.Rate(10) # 10hz
    while not rospy.is_shutdown():

        #query rosmaster status, which will raise socket.error when failure
        rospy.get_master().getSystemState()
        #end-of-checking

        str = "hello world %s"%rospy.get_time()
        rospy.loginfo(str)
        pub.publish(str)
        r.sleep()

if __name__ == '__main__':
    import time
    import socket
    while 1:
        try:
            talker()
            break; #normal termination, such as shutdown/ctrl-c
        except socket.error:
            time.sleep(1)
            print "reconnecting"

Just guessing here but what about NetworkSetup page? it didn't help you? there is an external tutorial about "Configuring /etc/hosts". Maybe that's the way.