Re: [gdm-list] GDM - gdmdynamic and Sun Ray support

[Bob Doolittle <Robert Doolittle Sun COM>]

(Jerry answered some of this already but my writeup
is focused more on the gdm/X interfaces so sending
it anyway).

William Jon McCann wrote:
> Hi Jerry,
>
> On 10/11/07, Jerry Wall <Jerry Wall sun com> wrote:
>   
> > The issue with Sun Ray and other thin clients is that there
> > is no local hardware and no kernel drivers involved in
> > plumbing one into the system. They are strictly network
> > connected client so there is nothing to tell something
> > like ConsoleKit about.
> >     
>
> Interesting.  The SRSS 4.0 Administrators guide (Chapter 4) seems to
> indicate otherwise.  What would be really useful then is a description
> of exactly how Sun Ray client and server software works and a link to
> the code.  Would you mind providing them?
>   

The code is proprietary at this time, I'm afraid.

In a small nutshell (and focusing on the DM/X
interactions), there is a "DDX" driver in the X
server that simply generates the necessary
rendering protocol and handles keyboard/mouse
event protocol directly over the network to a thin
client (and miscellaneous things like monitor
power management and LEDs).

SRSS handles rendezvous with a new thin client
when it connects to the server, and if no X
session yet exists and one is required it will use
gdmdynamic to tell the Display Manager to create a
new X session.  It will also put necessary state
information on the system for the DDX to use to
connect to the thin client when the X server
starts up.

If an appropriate X session already exists, SRSS
simply tells the DDX directly to connect the thin
client to it and gdm is not involved.  It simply begins
rendering to the new thin client.

Finally, a session may be torn down either due to
administrative action or when a session is sitting
at a greeter and has been disconnected for some
time (we instrument the gdm.conf file to create
entries for PreSessionScriptDir,
PostSessionScriptDir, and DisplayInitDir so that
we can know when a session is sitting at a
greeter).  Again, gdmdynamic is used for this
purpose (tearing down sessions).

Our thin client also handles audio and USB devices
but none of that involves gdm in any way so it's
not relevant.  Happy to discuss it if interested, however.
Suffice it to say that this is handled directly from user
space to the thin client over the network when possible,
aided by some trivial loopback drivers and some mass
storage glue (quite a bit less trivial).

-Bob

> It is pretty important that we understand what the particular needs are.
>
> Thanks,
> Jon
>