Include Common Node in Multiple .launch
I have a set of launch files that each of them initiate a subsystem. However, some of the .launch files contain dependencies on a subset of the system. I could include all dependencies in a .launch file and include it in all other launch files. However, for running the complete system, I include all .launch files in a "global" launcher. This causes the common nodes to start multiple times. How could I solve that? Is there any way to "declare once" some nodes?