clarity of concept

> This involves IPC, but also discovery and lifecycle problems. How do you locate and use a service? How do you ensure there's only one copy of a service? How do you close down all the services in a user session? Stuff like that

Aren't these problems already solved by sysadmins since long time in UNIX systems?

It has been normal practice to write files in /var/run/SERVICENAME.pid to store the pid of the process.. this gives you both a way to know if it's running and a way to send a TERM signal if needed.

Also, you can use UNIX domain sockets for communication with a service, as long as the path to the socket is agreed on (I guess you have to agree on a namespace for dbus anyway.. so what would be the difference?)

Are there really problems in UI development that do not happen for system processes?

I think that the real problem is that the Linux Desktop has been from the beginning setting itself apart from the Linux Server systems. Freedesktop.org only thinks on desktop systems, it never takes into account system services, I don't see any sincere attempt to get standard that would work for all the system tools as a whole and they completely disregards the UNIX philosophy.