[ros-users] Programmatically get ModelState from Gazebo

Hello, I am trying to programmatically get information about the pose of a
PR2 in Gazebo. The examples on the wiki seem to be based upon command line
using rosservice. Based upon the Publisher/Subscriber example on the ROS
wiki I would imagine it would be something like:

rospy.Subscriber("gazebo/model_states", Pose, callback)

but when I try something similar to this Gazebo sends and error msg and
breaks the connection. I would think it is just finding the right
combination of topic and msg but I am having troubles figuring that out. Any
help would be appreciate.