The Mercator System was designed to provide transparent non-visual access to applications built using the X Window System. By “transparent” I mean that the applications in use do not have to be rewritten to work with Mercator—any existing applications should work with the system without modification. To provide this access to applications, there were two major problems that we had to overcome. First, we needed a framework which would allow us to monitor, model, and translate the graphical interfaces of X Windows applications without modifying the applications. Second, given these interface models, we needed to devise a methodology for translating the original graphical interfaces into non-visual ones—essentially mimicking the advantages of GUIs in a non-visual presentation.
We wound up building several versions of the system. The first approaches used an X “pseudo-server” to monitor the X protocol stream between clients and servers. Based on our experiences with these early efforts, we proposed a set of modifications to the standard X platform. Many of these modifications have been released by the X Consortium as a part of the standard X distributions, starting in X11R6.
In 1995, the name of the system was changed to UltraSonix (to prevent us from stepping on the toes of an existing system called Mercator). Development at Georgia Tech halted at the end of 1995, as the primary developers moved on to new jobs. In 1996, a crew of intrepid hackers on the net got the source, and have been actively engaged in porting the system to new platforms (particularly Linux), removing dependencies on commercial software, and fixing bugs.
From day one, the project was a collaborative effort involving a good number of people. The folks that worked on the system at Georgia Tech include:
- David Burgess
- Kevin Chen
- Keith Edwards
- John Goldthwaite
- Stacy Ann Johnson
- Beth Mynatt
- Sue Liebeskind
- Tom Rodriguez
- Philip Seaver
- John Selbie
- Ian Smith
- Kathryn Stockton
Our sponsors were Sun Microsystems, the National Security Agency, and the NASA Marshall Space Flight Center.
While I was one of the principal developers of the system, and managed its development for the last year or so at Georgia Tech, I’m not involved in Mercator or accessibility work these days. Thus, I can’t support the software, and don’t have a lot of time to answer questions about it. The system is definitely “research-quality” software, so be forewarned. If you’re interested in using it, your best bet is to hook up with the crew doing the port. Their version of the software has advanced far beyond the original Georgia Tech version anyway. Mark Novak of the Trace Center is coordinating this development effort. The home page for the porting and development effort is here. Brian Sellden, one of the primary Linux hackers working with the code, has a page with progress reports and other information here.
If you want the source code of the Georgia Tech version it’s available here. This software is free for non-commercial use, but if you want to use it in a commercial product, bundle it with a commercial product, or make any money off it, you need to talk to the Office of Technology Licensing at Georgia Tech (call 404-894-9727 and ask for Kimberly Dunn). The full licensing text is:
The use of this program shall be restricted
to educational, non-commercial use only. All inquiries regarding
licensing this software for commercial use may be addressed to:
Georgia Tech Research Corporation
Centennial ResearchBuilding - Rm. 275
400 Tenth Street, N.W.
Atlanta, Georgia 30332-0415
The software is Copyright 1995, Georgia Tech Research Corporation, all rights reserved.
A pre-built binary for SPARCstations running Solaris 2.5.x is available here. It’s in Sun package format, so you can just use pkgadd to install it. A warning: configuring the thing for actual use is a bit tricky; you probably shouldn’t just assume that you can use this code to get real work done.
The old Georgia Tech web page on Mercator was still around, here (last time I checked, anyway), although it’s terribly out of date.
The list of papers about Mercator is rather long. Here’s the one’s I’ve been associated with:
(For a more complete list of my papers,