DM communication standard

[George]

On Sun, Aug 08, 2004 at 10:13:09PM +0200, Oswald Buddenhagen wrote:
> On Sun, Aug 08, 2004 at 10:40:31AM +0200, Raffaele Sandrini wrote:
> > There were some thoughts about this earlier but they never made it
> > into one of eather GDM or KDM.
> > 
> yeah, some 8 months ago ... on the bright side, i now actually did it. i
> had a deeper look at gdm's protocol and dismissed it for various
> reasons. what i did is more like kdm's old fifos (the commands are even
> backwards compatible), only with a new transport and a return channel.
> the code is in kdebase/kdm/backend/ctrl.c.

FIFOs?  Evil! :)

> > George, Oswald: I think you should reconsider this issue. As a last
> > resort, every app communicating with DMs could implement both, KDM's
> > and GDM's way doing that, but that is not really a resonable solution.
> > 
> yeah, i expect gdm to adapt kdm's new way. :-]=]
> i did this in a hurry without checking with george first, but judging by
> the conversation we had before i expect george will have no real
> objections against my stuff. the transport was already agreed upon and i
> made the protocol extensible (see "caps" command), so gdm can add stuff
> i left out in kdm (btw, "my" command set is not complete, yet).
> oh, george, now that i was pointed at your existance again ;), would you
> mind reviewing ctrl.c _r_sn, so i can pull the emergency brake before
> our release if necessary? not that the stuff is already documented or
> even used anywhere, but better if it's not there at all, if it's going
> to change anyway - i left kdm's old fifos in for now.

I will take a look at it ...

But I'm really not keen on using fifo's rather then a single socket.

Secondly: this is just the DM, there are only two and it's really really
really REALLY (did I meantion "really") low on my priority list to make gdm
change it's protocol.

Since the only reasonable application that ever wants to call this is the
session manager I don't see this as a big issue.

I think in the star trek future we should be using d-bus.  So this is the #1
reason why gdm is very unlikely to adapt another incompatible interim
protocol.  Basically, at some point when everyone and their mother is using
d-bus, then I'm sure both me and oswald will go "oh yeah we should use that"
and we'll implement that.  Since I think this will happen at some point, I
consider any other change in protocol temporary and thus unnecessary and a
complete waste of time unless it does something new and cool and I can't
imagine it does :)

In the meantime I think gnome-session and the kde session manager should just
implement both protocols.  That is far less coding then changing gdm.  And it
doesn't break anything while changing gdm does.  If in the meantime either
gnome-session nor kde session really implements the other, it is no biggie.
All that happens is that the user will have to log out and then select "Shut
down" from the login screen.  I think the 95% percent use case is when a
gnome user uses gdm and a kde user uses kdm, so those are the cases that need
attention now.  IMO anyway.

George

-- 
George <jirka at 5z.com>
   In the fight between you and the world, back the world.
                       -- Franz Kafka