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Hi all,
I have a question about how nodes are implemented in ROS. From what I understand the "type=" definition refers to an executable file that ROS runs. Consider this example:
<node name="robot_state" pkg="robot_state_publisher" type="robot_state_publisher"/>
Now when I go into the robot_state package I don't find an executable called robot_state_publisher. Would anyone care to explain why that is?
Regards, Devin
You are right, type="<EXECUTABLE>".
The robot_state_publisher is defined in the robot_state_publisher package (not robot_state, this is just a name for the node).
However, if you install executables from apt-get (or build them yourself), they don't end up in the package, but in /opt/ros/<DISTRO>/lib/<PACKAGE>/<EXECUTABLE> (or <CATKIN_WS>/../devel/lib/<PACKAGE>/<EXECUTABLE> if you compile it yourself).
However, nodes need to be implemented in a special way. Check out this tutorial for a simple example. Make sure to read the in-source comments.
The executables are not stored directly in the package directories. They are stored in a "lib" directory. Try "ls /opt/ros/$ROS_DISTRO/lib/robot_state_publisher" and the executable "robot_state_publisher" should be in there.
This is also the case in your catkin workspace. When you do "catkin_make", it doesn't place each executable in its corresponding package's directory. It places them in the "devel/lib/" folders of your catkin workspace.
Asked: 2015-10-27 09:13:22 -0500
Seen: 165 times
Last updated: Oct 27 '15
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