Viewing custom messages from a ROS node that is on a different ROS install

edit

Thanks that makes sense.

I keep all of my code in a github repo, I have just created a new package with the postfix _msgs to store messages - and with that a second git repository. Is it also best practice to distribute code like that? One repo for the messages package and one for the main package?

Depends. Some ppl like to keep _msgs pkgs in the same repository as the nodes that use that pkg, to make releases easier (_msgs is dependency of other pkgs, so needs to be released first). Others like to separate. Smallest re-usable artefact vs distribution convenience is always a trade-off.

Note that if you release the pkg (through the ROS buildfarm), it doesn't matter (for your users) whether the pkg is in a separate repository or not, they can always install your _msgs pkg separately.