On Tue, Mar 23, 2010 at 3:30 AM, Ugo Cupcic wrote: > I was wondering how I can achieve to have different callback functions > on the same topic depending on the message types. hi Ugo, In ROS, a topic can only carry messages of a single type. We decided early on that it would be too confusing if a topic could be of multiple types. So roscpp doesn't support multi-type callback registration. (Note that the type of a topic actually can change over time, as it's determined by the publisher that most recently advertised the topic. But in a well-behaved ROS system, topics are stably typed). brian.