Have the Session object provide methods for retrieving information about other applications

[eflumerf]

Several SmartDaqApplications need information about other applications in the Session to set up network connections. (e.g. https://github.com/DUNE-DAQ/appmodel/blob/f0eee9340ab38266abaed96d6a85d16d9b22d1e9/src/DFApplication.cpp#L261)

The Session object should be able to provide this information, so that SmartDaqApplications (and DAQModules) can remain ignorant of the state of the rest of the system.

[gcrone]

I think this really needs to have NetworkRule and SmartDaqApplication in the confmodel package. This is not feasible while we are using the current hack to call the appropriate get_modules() method in SmartDaqApplication. It should be OK if/when we start using the thea/virtual_strikes_back branches.

[mroda88]

Hi all, quick follow up on this. Now that we are using correct virtual, can we review the feasibility of this task?

[gcrone]

I think it is feasible to move the SmartDaqApplication and NetworkRule classes into the confmodel package now but I'm not sure that is what we want to do. I did have another approach to providing access to information from other applications in DUNE-DAQ/appmodel#171 where a helper class is defined in appmodel and the applications don't even see the Session object.