Using keys for this use case has one drawback. Keys are not "introspectable" without receiving the actual data. You can't answer the question what parameters exists - without actually receiving all the parameter values first. So if you would like to implement a user interface which should show the name of all parameters you can't do that efficiently. Imagine some parameters contain large data but the user only wants to see the names of all parameters and then decides to get only the "small" value of one of the parameters. --- [Visit Topic](https://discourse.ros.org/t/keys-in-msg/1942/4) or reply to this email to respond. If you do not want to receive messages from ros-users please use the unsubscribe link below. If you use the one above, you will stop all of ros-users from receiving updates. ______________________________________________________________________________ ros-users mailing list ros-users@lists.ros.org http://lists.ros.org/mailman/listinfo/ros-users Unsubscribe: