[ On Saturday, June 15, 2002 at 11:49:27 (-0700), Andrew Gillham wrote: ]
> Subject: Re: Terminal Server
>
> No offense, but I have to disagree with you.  Saying that X is equivalent
> to Windows Terminal Server is just plain wrong.  The correct comparison would
> be with VNC.

Huh?  VNC still needs an Xserver image to mirror.  Where do you propose
to run that Xserver?  What difference do you perceive between running a
virtual Xserver on the server and local Xserver on your client?

>  The biggest (IMHO) advantage of WTS is that if you get dumped
> on your dialup or some other event that causes your session to get disruped,
> you can reconnect _exactly_ where you left off.  E.g. the application state
> exists only on the WTS box.  This precisely how VNC works on Unix.

Hmmm... OK, but there are other solutions to this problem.

The performance advantages of running X11 with a separate CPU running
the local Xserver, instead of VNC, can be quite stunning when you're on
a low-latency LAN connection (provided of course that you're not trying
to do bandwidth-heavy multi-media things, or integrate other graphics
programs into your desktop where those other programs will try to make
direct use of the display hardware to accellerate their operations.

Over dialup there are debates about which is a heavier-weight protocol,
but with low-bandwith-X and other compression techniques I think X11
still comes out the winner.

> Suggesting that the X Window System's remote display capability is equivalent
> is not appropriate, IMHO.

In the unix world the X Window System delivers the equivalent
functionality, even if not with the same implementation quirks.  I think
it's an entirely appropriate comparison.

>  If your X Window Server loses contact with the
> machine(s) running the X Window Clients, you're totally hosed.

That's not true at all.  I can unplug my Xstation from the net for many
minutes and then plug it back in and continue working (sometimes the
client detects loss and asks me if I want to reset my session, but
provided I don't allow that then everything keeps working just fine).
Even over a WAN connection it's possible to restore connectivity and not
lose X11 client connections (unless you're using something like SSH to
tunnel connections and the sshd process on the client machines dies, in
which case the clients suddenly lose their connections too).

If I reboot my Xstation then, yes, my clients will normally die and
even if they don't they cannot be re-connected in exactly the same state
as before.

However X11 has progressed to a point where the client programs are
getting pretty good at saving state and starting back up again where
they left off.  Why even emacs has "recover-session" now!  ;-)

> I'm not saying the WTS model is better, just saying it is equivalent to VNC,
> not X itself.

Which is why it's so brain-dead right from the design on down.... :-)

-- 
								Greg A. Woods

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