per-user dbus

Havoc Pennington havoc.pennington at
Wed Nov 11 07:40:09 PST 2009

There's a ton of user bus discussion in archives. While there are some  
use cases most of the good ones require a true user bus not a user- 
machine bus. Let's face it most things are per user on all machines or  
per all users on one  machine.

I think a user bus would attract stuff that should be designed per  
session. Having session and system already confuses the hell out of  

It's just too complex relative to value.   Work around its absence.  
That's my opinion.

If you did do it, name it user-machine bus not user bus please.

On Nov 11, 2009, at 9:51 AM, Ray Strode <halfline at> wrote:

> Hi,
> On Tue, Nov 10, 2009 at 10:37 AM, Colin Walters <walters at>  
> wrote:
>> On Mon, Nov 9, 2009 at 5:16 PM, Lennart Poettering <mzqohf at 
>> > wrote:
>>> While some folks seem not to particularly like the idea (Hey,  
>>> Colin!)
>> Well, it's not that I don't like the idea of a per-(kernel,uid) bus,
>> it's more that I think that's what the "session" bus should be.
>> In other words, if we have _USER, what should still be using  
> The session bus serves a very useful purpose, it defines the scope of
> the user's session.  I think that was one of it's original design
> intents (right Havoc?).
> There are various bits of infrasture that hook themselves to the
> lifecycle of the bus because they expect that the bus will only
> survive for the duration of the user's session.
> I don't think we can break that gaurantee.
> Having a separate user bus may make sense for limited number of cases,
> but i don't think it makes sense to replace the session bus with a
> user bus.
> What might make sense is having a way for programs to add themselve to
> the session without their parent being in the session.  I could
> imagine, if DBUS_SESSION_BUS_ADDRESS wasn't set, looking for the first
> available running session bus for the user (how? kernel keyring? X
> property?) and joining it.  This would solve the
> cron-can't-access-my-session-even-when-i'm-logged-in problem.
> Although, I think that problem would better be solved by
> gnome-settings-daemon or some other session daemon just providing cron
> like functionality.
> I do think the number of cases where a user bus is useful is pretty
> small.  I'm not saying those cases are invalid, but we shouldn't try
> to shoehorn other cases into the user bus bucket.
> --Ray

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