Revision history [back]

In other words if a topic is not needed on the network, does it get published on the network?

'needed' is a bit vague, but if no one is subscribing, no data is sent over the network. Period.

This is also answered by @dornhege in the question you linked:

First, if no one is subscribing over the network, then nothing should be happening when you publish, i.e. if network bandwidth is wasted somewhere, there must be some connection between a publisher and subscriber (rviz counts!). This is already somewhat implicitly in the core code as if there are no connections, there is no where to send to.

If you feel this is not an adequate answer, can you please clarify why you still have doubts about that?