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RE: [seul-edu] I love progress

On Tue, 21 Mar 2000, you wrote:
> On Tue, 21 Mar 2000, Jason Mellen wrote:
> > I like it. This will be great for many things I need to do except for a
> > school setting I need something that can support multiple users. Is there
> > something that I'm missing about this? 
	Yes ;-).  VNC works very much like regular X, only it exports an
_entire_  X-windows session rather than individual applications. You can setup
a VNC server on a Linux box and have it serve out several X-sessions(you're
not limited to 1). I believe that the windows VNC client has a full-screen
option. Once that's enabled, It'll look just like you're sitting a Linux
station. The only disadvantage to using this approach is that you need to run
(at least) a window manager in addition to whatever applications you wish to
use. Odds are though, that's what you wanted to do anyway. From what I've read,
VNC should use less bandwidth than X and provide just as much funcionality.
Plus you get the added bonus that there are free clients for virtually every
type of machine (win32, mac, *nix). Last time I used it, I remember spending a
few hours reading the docs but was _very_ pleased with the results.

> >With X, you only have to have the
> > program running on the server not one for every user. What are your thoughts
> > on that?
> You're comparing it to a bunch of X terminals right? If so, I don't think
> it's much different. Twenty people running Netscape remotely through X
> terminals will cause twenty copies of Netscape to run on the server (file
> server, that is). Now I know programs that can utilize shared libraries can
> do this a little better, but statically linked apps are going to be a pretty
> big load on the server.
	The linking mechanisims have zero effect on the load when multiple
instances of the program is run. Linux/Unix has some nifty features when it
comes to memory management. As you likely know, the actual program's code does
not change as the program is executed, therefore, there is no difference
between the Netscape code for user A as opposed to user B. Linux realizes this
and loads only a single copy of netscape into memory; then, it does a little
bit of memory magic and makes it look as though it's loading multiple copies
even though only one exists. 
	That said, you still have to worry about _dynamically_ allocated
memory. That must still be done on a per-user basis :( So while you don't have
to worry about program size overlymuch, the rest of it is still an issue.

> That said, I've never tried either approach. I use VNC primarily so I can
> use a Win95-based gradebook program remotely from the Linux box on my desk.
> VNC is fast enough to be tolerable on a 10base-T, non-switched LAN.

	There's a page on AT&T's site that has dozens of tips for speeding VNC
up..... they make a HUGE difference. Anyone considering using VNC should at
least skim through it.