Path: utzoo!mnetor!tmsoft!torsqnt!news-server.csri.toronto.edu!cs.utexas.edu!usc!apple!sun-barr!newstop!sun!amdahl!ntmtv!hopper
From: hopper@ntmtv.UUCP (Ian Hopper)
Newsgroups: comp.windows.x
Subject: Re: Spy X Window
Message-ID: <1430@ntmtv.UUCP>
Date: 22 Jul 90 05:30:42 GMT
References: <194@melpar.UUCP>
Organization: Northern Telecom, Mtn. View, CA
Lines: 50

From article <194@melpar.UUCP>, by jim@melpar.UUCP (Jim Hopkins):
> 
> I need some X help.
> 
> I want to "monitor" a window on another machine from my machine.
> I have source for all software running but would rather not modify any of it.
> I have full control of unix permissions etc.
> 
> Ideally I'd like to tell the server on the other machine to duplicate the 
> window on my display. I need no control over the "copied" window but I would
> watch what someone else was doing and see all updates to this window. It would
> be teacher/student type situation where the teacher can spy on the students
> progress/work habits.
> 
> Perhaps I'll need an application that can decode names into window IDs on
> the other machine--that would be fine.
> 
> Any hints or solutions would are appreciated.
> Thanks
> 
> Jim Hopkins	uunet!melpar!jim
If you happen to be on SUN's, I have used a simple approach that is not
dependent upon X: "rsh <student-machine> screendump | screenload".
The effect is to transfer a snapshot of the student's screen, and display
it on the teacher's machine.  We have a homogenous SUN 3/60 environment, so
it works very well. The concept may be applicable to your needs.

If you need a real X solution, there is a special X-Server called SharedX
which does what you want plus gives the teacher shared control over the
application.  I have not heard much about SharedX for more than a year.
Perhaps the kind soul that is maintaining it could speak up and offer an
anonymous FTP?  Last I heard some folks at HP Labs were working on it.

If you have the energy you might consider hacking the X10/X11 emulator
package to give yourself a Virtual-X-Server that creates the extra windows
that you need.  Most solutions (including SharedX) to your problem are of
the form of a "Virtual X Server" that looks enough like an X-Server to
fool the application, but is an application itself with respect to the
real X Server(s ) that are actually running the displays.  The virtual server
you want is one that intercepts window updates and performs the identical
updates on both the student's X server and the teachers X server.
The difficult problem that SharedX tries to solve is the problem of gathering
input from multiple real X servers and presenting that input to the X
application in a consistient fashion.

Good luck, post the results of your investigations...

-- 
Ian Hopper		{amdahl.com,ames.arpa,hplabs}!ntmtv!hopper
Northern Telecom Inc.	[Clever comment under construction.]