D-Bus User Bus

Havoc Pennington hp at pobox.com
Wed May 19 19:19:41 PDT 2010


On Wed, May 19, 2010 at 10:11 PM, Lennart Poettering <mzqohf at 0pointer.de> wrote:
> You are writing this as if there was any value in strictly seperating
> multiple sessions of the same user from each other. But there is none.

The value is: it's a simple model that matches the X server model, so
X server and dbus-daemon are co-scoped. Historically people understand
this and it works. It's also what's documented and how it's worked for
a long long time.

If you go per-user (instead of per-session; an alternative would be in
addition to per-session, at complexity cost), then now you have the X
server with behavior/scope A and dbus-daemon with behavior/scope B,
and they don't have the same lifetime. That is harder to understand,
and for most GUI apps, not what is wanted. It's also an ABI break,
pretty much. I would predict that tons of stuff assumes the session
bus has session scope.

*Adding* a per-user bus is less disruptive, but then you have to ask
whether it's really worth having yet another bus, or whether the
system or session bus could be made to work for the per-(user,machine)
case and I think they pretty much can. But adding a per-user/machine
bus is certainly more sane, imo, than replacing the session bus. I
don't think *adding* the per-user bus is broken, just kind of
overkill; *converting* the session bus to per-(user,machine) I think
is likely to end up pretty broken. But, maybe nobody cares about
network homedirs anymore. I haven't used one personally in many years.


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