some question about the nodes and topics in ros_industrial_client package

edit

Hi! I read the industrial_robot_clientgeneric_implementation(http://wiki.ros.org/industrial_robot_client/generic_implementation)and have some confusion about the nodes and topics mentioned in this page.

1.In this page, there three nodes,robot_state,motion__interface and joint_trajectory_action. The robot_state just publishes three topics without subscribing anyone topics while motoin__interface is completely opposite. Does the robot_state node decode the message received from robot controller using simple message? And the motion_*_interface subscribes the message form topics and encode them using simple message then send to robot controller? Can I understand the process of these two nodes like this?

1. Does joint_trajectory_action node act as an action server?I noted that this node subscribed topics like goal, cancel and states and publishes topics like feedback, status etc.where is the action client? 3.I'm a beginner so I still don't know how to understand the whole process of the implecatioin process and of industrial_client and simple_message,so I hope someone can give me some suggestions. Thanks!