Re: server query -- inherent UNIX XDM/XDMCP v. MultiWin

["Bryan J. Smith" <b.j.smith@ieee.org>]

On Thu, 2004-12-23 at 14:57, bentley_rhodes wrote:
> i do not ask for directions as how to achieve this, i only ask if it is 
> possible.  is it possible, and fairly simply (or not) to install all 
> programs onto the server computer and acess them (start them) from 
> another computer located upstairs?

Yes.  This is _native_ and _inherent_ to UNIX/Linux.  Both for console
(text) and X11 (GUI) access.

Microsoft calls this "Terminal Services," which is actually an
assimilation of Citrix "MultiWin" technology which they sell in their
add-on "MetaFrame" products.

Long story short, NT (FYI, NT5.0=2000, NT5.1=XP/2003) was designed to
_require_ 1 physical VGA card to 1 physical user with 1 physical
display.  This is known as the GDI (graphical display interface). 
"MultiWin" is a hack to NT created by Citrix to allow virtualized GDIs. 
"MultiWin" is now included as standard in NT5+, but you can only allow 1
user (remote administration) in XP Home, or 2 users (administrative
mode) in 2000/XP Pro and for more than 2 users, you must license
"Terminal Server" licenses (even if you use MetaFrame atop of that).

On UNIX, we do not require _any_ console at all.  But by default in
Linux, we allow up to 256 "psuedo terminal" connections.  These could be
local consoles, remote consoles (telnet, SSH, etc...), local X11
input/output (video card-monitor, keyboard/mouse) or even remote X11
shells/displays/etc...

> including, say at boot time the upstairs computer opens or logs on
> to the computer in the downstairs?

Yes, using XDMCP, you can actually launch a X11 (GUI) session on the
"server" computer that displays on the "local" system.  I.e.,
_everything_, from the GUI "shell" (window manager) to _all_ programs
are actually running on the "server" computer.  The "local" system is
merely providing the input/output interface.

Or you can run your X11 "session" locally (using the XDM, GDM/Gnome or
KDM/KDE "session manager"), and then SSH into the "server" computer. 
You can then launch a program by merely typing something like "firefox
&" and it will launch firefox on the "server" computer and display it on
the "local" system.

XDMCP -- whereby you launch an _entire_ "remote desktop" on a local
system is akin to Windows Terminal Services.  We call this "Root X11" --
meaning the entire "root" X-Server is remote.

Regular X11 operation -- whereby you merely launch a program on a remote
system is akin to Citrix MetaFrame in "Seemless mode."  We call this
"Rootless X11" -- meaning the "root" X-Server is loca, so the X11
programs are running over the network "rootless."

-- 
Bryan J. Smith                                    b.j.smith@ieee.org 
-------------------------------------------------------------------- 
Subtotal Cost of Ownership (SCO) for Windows being less than Linux
Total Cost of Ownership (TCO) assumes experts for the former, costly
retraining for the latter, omitted "software assurance" costs in 
compatible desktop OS/apps for the former, no free/legacy reuse for
latter, and no basic security, patch or downtime comparison at all.




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