I would go further with your idea. You should have all I/O separated and in on place. UI is just a special case of I/O for apps. In services you also want to k

I would go further with your idea. You should have all I/O separated and in on place. UI is just a special case of I/O for apps. In services you also want to keep all RPC handlers in on place (or any interface with which others interact with your binary). You also want to keep any interfaces with which you make IPC calls each separate and in one place as well. I use IPC (inter process communication) as this includes service clients, database clients, disk access, peripheral access, etc as well.