dbus, hal over xdmcp?

[Anton Shterenlikht]

On Tue, Jun 16, 2009 at 04:21:42PM -0400, Joe Marcus Clarke wrote:
> On Tue, 2009-06-16 at 10:57 +0100, Anton Shterenlikht wrote:
> > On Sat, May 02, 2009 at 05:56:53PM -0400, Joe Marcus Clarke wrote:
> > > On Thu, 2009-04-30 at 15:27 +0100, Anton Shterenlikht wrote:
> > > > On Thu, Apr 30, 2009 at 09:08:39AM -0500, Robert Noland wrote:
> > > > > On Thu, 2009-04-30 at 03:34 -0400, Joe Marcus Clarke wrote:
> > > > > > On Tue, 2009-04-28 at 14:30 +0100, Anton Shterenlikht wrote:
> > > > > > > On Fri, Apr 24, 2009 at 01:38:58PM -0400, Joe Marcus Clarke wrote:
> > > > > > > > On Fri, 2009-04-24 at 12:27 +0100, Anton Shterenlikht wrote:
> > > > > > > > > I've read the dbus and hald man pages but I'm still confused.
> > > > > > > > > 
> > > > > > > > > In a configuration where xserver connects to clients via XDMCP
> > > > > > > > > where do I need to run dbus and hald, or more specifically, on what
> > > > > > > > > computer do I need to have in /etc/rc.conf these two lines: 
> > > > > > > > > 
> > > > > > > > > dbus_enable="YES"
> > > > > > > > > hald_enable="YES"
> > > > > > > > > 
> > > > > > > > > 
> > > > > > > > > a. only on the machine which runs xserver?
> > > > > > > > > b. only on the machine which runs the clients?
> > > > > > > > > c. on both the xserver and clients machines?
> > > > > > > > > 
> > > > > 
> > > > > As far as keyboard and mouse are concerned these are client side
> > > > > devices.  The server itself can be run headless, though it has been a
> > > > > very long time since I've done anything like that...  You might need hal
> > > > > on the server side for things like auto-mounting server side cd's or
> > > > > whatever, but not for kbd/mouse.
> > > > 
> > > > I understand this refers to hal, isn't it?
> > > > 
> > > > But dbus is about interprocess communication, and the processes are
> > > > run on a remote box. So should I run dbus daemon on the remote box
> > > > as well, or instead of, the xserver box?
> > > 
> > > You need to run on both.  The process address space is still on the
> > > XDMCP server, so the system daemon must be running there.  The clients
> > > have mice and keyboards so they need dbus and hald.  You will also need
> > > to start your dbus-enabled processes with dbus-launch, or start your
> > > local X session with dbus-launch so that a session bus is running.  This
> > > session bus will also be running on the XDMCP server.
> > 
> > Both hal and dbus daemons are running on both the X server and XDMCP server.
> > And I launch the session with:
> > 
> > %head $HOME/.xsession
> > dbus-launch --exit-with-session mwm
> > 
> > Still on the XDMCP server I just see:
> > 
> > # ps ax | grep dbus
> >   594  ??  Is     0:00.02 /usr/local/bin/dbus-daemon --system
> > 98706  ??  S      0:00.04 dbus-launch --exit-with-session mwm
> > 98709  ??  S      0:00.00 dbus-launch --exit-with-session mwm
> > 98710  ??  Ss     0:00.00 /usr/local/bin/dbus-daemon --fork --print-pid 7 --pri
> > 98712  p0  R+     0:00.00 grep dbus
> > #
> > 
> > and on the X server I just see black screen. I can move the mouse, but
> > nothing happens with any clicks.
> > 
> > If I start the session with no dbus-launch, I can use mwm fine, but no
> > dbus.
> > 
> > What else can I check?
> 
> You could try leaving out --exit-with-session.  Of course, there may be
> a problem with your dbus installation.  This should just work.

no, that doesn't work either.
I wonder if anybody has actually successfully used dbus with XDMCP.
I know it should work, but maybe nobody has tried, so perhaps there
are some issues.

I have a user group of about 20 people, all under the university firewall,
so insecurity of XDMCP is not a major concern.
I was thinking of having a powerful XDMCP server as an energy efficient
and easy to maintain model, since the desktops only need to have a good
graphics card. If that is not working, then perhaps I have
to switch to plain ssh tunneling, and have full X installation on all
desktops. 

-- 
Anton Shterenlikht
Room 2.6, Queen's Building
Mech Eng Dept
Bristol University
University Walk, Bristol BS8 1TR, UK
Tel: +44 (0)117 928 8233 
Fax: +44 (0)117 929 4423