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

[Bob Doolittle <Robert Doolittle Sun COM>]

Thanks Brian.

Taking a step back, a Sun Ray is just an example of a "Thin Client".
All Thin Clients can dynamically attach to servers and need a desktop
served to them when they do.  gdmdynamic is the interface
used to setup and tear down desktops when needed.  For the purpose
of GDM, I don't want to over-focus on Sun Ray (even though it's
the product I work on), the value of gdmdynamic is (at least
potentially) broader than that, and should remain so.

Here's a blog entry regarding Sun Ray for home use in case
that's of interest in putting this into perspective:
http://blogs.sun.com/bobd/entry/the_real_definition_of_sun

There are some interesting announcements coming out soon
which may make in-home use more attractive.

-Bob

Brian Cameron wrote:
> Jon/Others:
>
> Since things are still in the early stages of the GDM redesign, it
> probably makes sense to try and hammer down the requirements for
> gdmdynamic and Sun Ray a bit better.
>
>    http://www.sun.com/software/sunray/index.jsp
>
> Note that Sun Ray Server Software (SRSS) is available for free to Linux
> users, and such users also depend on GDM for this to work:
>
>    http://wwwcip.informatik.uni-erlangen.de/~simigern/sunray-debian/
>
> In short, the way that Sun Ray works is that the Sun Ray server may
> have some displays attached directly and these are treated like normal
> displays by GDM.  In other words DISPLAY :0 may be a monitor actually
> attached to the Sun Ray server machine.
>
> In addition, the Sun Ray network may have any given number of Sun
> Ray client devices attached to the same network as the server.  The
> client devices let the server know that they are present over the
> network, and the server sets up the device so that it appears as a
> normal X display to the server machine, even though the device is
> actually located over the network.  So, the Sun Ray server might
> treat the first one it discovers as display :100, the next as :101,
> etc.  Upon discovery, the Sun Ray server software tells the display
> manager to start managing this display.  When it is time to stop
> managing a display (like if it gets unplugged), the Sun Ray server
> likewise tells the display manager to stop managing this display.
> The gdmdynamic program is used for managing and unmanaging these
> displays.
>
> This functionality might be of general use outside of a Sun Ray
> context.  I am not aware of anybody using this for other purposes,
> but there may be other situations where it might be of value to be
> able to control when various displays are managed or unmanaged.  I
> could imagine that other multi-user terminal-server type environments
> might find some use in this sort of functionality if they wanted to
> support the ability to hotplug displays like Sun Ray does.
>
> Because testing this with an actual Sun Ray network is cumbersome, I
> wanted to share with you the attached tarball which contains scripts
> that allow you to simulate a Sun Ray environment using Xvfb.  This
> is also useful for stress-testing GDM in a multi-user environment
> where the daemon needs to manage a large number of displays, like
> in a terminal server situation.  There also might be some value in
> being able to manage virtual displays using this sort of technique
> in general, perhaps for automated testing.
>
> The tarball contains a README which explains some of the internal
> details of gdmdynamic and how to set up the scripts to work using
> the GDM stable branch.  I just tested it with GDM 2.20 and verified
> that these scripts work okay.  Perhaps seeing the code actually work
> might help clarify the requirements.
>
> Jon, I was hoping this might help you understand how Sun Ray works
> with GDM.  Since I know you are focusing on the core stuff, perhaps
> we could discuss further how this should be implemented in the new
> GDM.  Perhaps this is something you would want to tackle, or if you
> want someone here at Sun to do this integration, then perhaps you
> could explain how you think this should fit in with the new
> architecture?
>
> I'm sure the Sun Ray team would prefer if the interfaces they
> depend on (namely gdmdynamic) were to remain stable.  However, if
> there is a compelling reason to refactor or redesign how the Sun
> Ray software interacts with GDM, then we can explore this also.
> I suspect the Sun Ray team would be agreeable to changes in the
> interfaces if there is good reason, and if it is possible for
> them to tell at runtime which interfaces to use, depending on
> what version of GDM is running.
>
> Brian
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