Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!sun-barr!lll-winken!elroy.jpl.nasa.gov!sdd.hp.com!spool.mu.edu!agate!dog.ee.lbl.gov!nosc!spectra!scott From: scott@spectra.com (Tim Scott) Newsgroups: comp.windows.x Subject: Summary of info on "Shared X" systems [130 lines] Message-ID: <1991May24.170050.25768@spectra.com> Date: 24 May 91 17:00:50 GMT Sender: scott@spectra.com (Tim Scott) Organization: Spectragraphics Corporation Lines: 121 I have received quite a bit of mail about the "shared X" facilities. Essentially, I was asking about software that would allow a client to display simultaneously on more than one display. Note: this is a long [100-140 lines] posting. The first place to look is always the monthly FAQ posting. Here it is: ------------- Subject: 76)* How can I "tee" an X program identically to several displays? There are several protocol multiplexer tools which provide for the simultaneous display of X clients on any number of machines. XMX (an X Protocol Multiplexor) is available from wilma.cs.brown.edu (128.148.31.66) as pub/xmx.tar.Z SHX from Michael Altenhofen of Digital Equipment GmbH CEC Karlsruhe also does this; it is a "WYSIWIS" (What You See Is What I See) package in the context of a computer-based learning/training tool to provide online help from remote tutors but is also useful for general window sharing. Information: shX@nestvx.enet.dec.com. SHX can be found on export and gatekeeper.dec.com:/pub/X11/contrib/shX.tar.Z, crl.dec.com:/pub/X11/contrib/shX.tar.Z XTrap is implemented as a server/library extension. It is available as: gatekeeper.dec.com pub/X11/contrib/XTrap_v31.tar.Z export.lcs.mit.edu contrib/XTrap_v31.tar.Z ------------- Here is some more information about the above applications and others that I received as responses to my posting. (And from other sources). 1. Shared X (Hewlett-Packard Co.) Hewlett-Packard Co. has a commercial product, "Shared X" which works under HP-UX currently on their 300 and 400 series workstations. The product number is B2305A for the media and manuals ($495) and B2305L for the license. Pricing for licenses is as follows: qty 1-7 $495 each, 8-user $3300, 24-user $9000, 48 user $15000, 96 user $25000. They do not recommend more than 4-5 users for CAD/CAM applications. A version for their 700 and 800 series workstations will be released towards the end of 1991. If I understand the analyst I talked to, it works by temporarily replacing the X server with a special one (saving the original to disk) and restoring the original when the session is done. This requires 3 MB of disk space for this swapping. ------------- 2. Shared X (Michael Althenhofen) This is a modified X library (shXlib) which can be used to provide "naive" X applications with the capability to work with several displays simultaneously, dynamically add and remove new displays, and hand input control from display to display. Since it is a library, you must have the source of the client to relink. It was part of Herr Altenhofen's diploma thesis work and was finished about a week before X11R4 was released. "It may be generally useful for group work and presentations. Currently there's very little documentation (we are writing a report of the work) and it surely is somewhat buggy." ------------- 3. xmx (John Bazik) This is a protocol multiplexor which is independent of the server and does not affect the application being shared. It was developed at Brown University for use in their electronic classroom, and (some form of it) has been in use since 1988. Author John Bazik states: "I'm currently working on version 2, to be released sometime this summer, which will fetch your slippers and pour you a cup of coffee. It addition to the things listed in the README file [including support for "late joiners"], it will support "passing the floor" (allowing another particpant to gain input control." Cameron Humphries reports: "Basically it pretends to be a server and you run your application as if xmx was the display. xmx then accepts requests from the client application and forwards them to all the displays it controls. It accepts responses from the [paticipating] displays but ignores all but those from the master display, which then gets sent back to the client. xmx also has the option of mirroring all mouse movements on all displays (a bonus in our case). The only downfall occurs if the users who are supposed to be viewing the demonstration move the window somewhere else... We combat this by sharing the window manager from the master and this doesn't allow the users to do anything at all. Probably its other minor bug is that it doesn't speak Xdmcp so you need to kill xdm on all screens you want to control first." ------------- 4. X conferencing project (UNC) jeffay@cs.unc.edu writes me that a group of researchers at UNC have developed/are in the process of working on a facility "for sharing the output of an X client among multiple X servers. The result is a system that allows multiple users to interact with a generic X client. We refer to such multi- user interactions as a 'conference.' Our system is distinguished by the fact that we've solved a number of hard/awkward problems that other's haven't addressed (like the ability to allow remote users to join a conference already in progress.) "The system runs under X11R4. We've been using it on Sun-3s, Sun-4s, DEC 3100s, and the IBM RS/6000." ------------- 5. Unknown I received some mentions of other possible systems, but I haven't yet received any information about them. These may not even be X based, but might be groupware. For your information, here is the list: XVT feit@cs.odu.edu Hussein M. Abdel-Wahab, Dept of Comp Sci, Old Dominion Univ., Norfolk, VA 23429, USA Dialogo Lantz and Lauwers [1988], Olivetti Research Center Shadows John Patterson Bellcore, 445 South St., Morristown, NJ 07962-1910, USA Rapport J. R. Ensor AT&T Bell Labs, Holmdel, NJ 07733, USA Thanks to: Cameron Humphries cameron@cs.flinders.oz.au John Bazik jsb@cs.brown.edu jeffay@cs.unc.edu and anyone else who I may have omitted.