Implementation of Webspace Visualization

v 0.5 BETA

by Ed H. Chi chi@geom.umn.edu

Computer Science Dept.

The Geometry Center, University of Minnesota

INTRODUCTION

This is the first BETA release of a Webspace visualization program that works in conjunction with WebOOGL. WebOOGL is a language that has been proposed as the standard for VRML. Using WebOOGL and our WebOOGL perl scripts, GeomView can be used to visualize Webspace by traversing the Webspace and generating the appropriate visualization.

This release is intended for hackers and developers who might be interested in how WebOOGL can be used. It is not yet meant to be used by end-users.

IMPLEMENTATION

A brief introduction on how Webspace is implemented.

The Webspace is really a directed graph. However, since the layout of directed graph is extremely difficult (a graph layout problem that has been studied for years), I chose to visualize the webspace by reducing it to a tree structure. Any edge leading back to a node that has already been discovered is eliminated.

The implementation of Webspace is simple. It first discovers the structure of the webspace by using the "explore" perl script written by Oscar Nierstrasz (oscar@cui.unige.ch). Once the data is acquired from traversing the webspace, the geometric structure is written out to a WebOOGL file, where each tetrahedron has a URL associated with it. The label for each node/tetrahedron is written out to a seperate label file, where each label file contains all the labels for a particular level of the tree.

With the labels in different files, it allows us to define widgets in 3d space, which when the user selects it, the approriate label file is added into the scene as a Geomview object.

The "explore" perl script has been hacked by me to give me the information I wanted. It also writes a few debugging files:

explore.stderr, explore.html, weboogl.host, weboogl.info.*

In addition, the explore script requires url.pl, http.pl, html.pl to run correctly. Perl must be able to find it.

The program was developed on a SUN SPARC 10 station. I've not tested whether it compiles on SGIs, but it should compile out of the box. This program is put under the GPL. However, if you would like to make modification to the program, I would like to know about it and incorporate into the standard release.

USAGE

usage: webspace [options] -h [http] -n [filename] [URL]

The following is required on the command line:

-h [http]

Specifies the http directory where the final webspace files will reside. (e.g. http://www.geom.umn.edu/docs/chi/) This is needed because the geometry specification file must know where the label files reside.

-n [filename]

Specifies the beginning of the output filename (the file generated would be called filename.oogl)

[URL]

A URL specifying an HTML document. If it is a server address, it must end with an "/". (e.g. http://www.geom.umn.edu/, and not http://www.geom.umn.edu)

Options:

-d

turn debug on

-l [number]

specify the number of levels to traverse (default 2)

-s [server]

specify the Server to limit the robot to

Comments are welcome. If you think the program is good enough for celebration, I won't be sad if you send beer fund, postcards, creditcards, sound and graphic boards, scsi-2 or ethernet cards to me. :)

THE AUTHORS DISCLAIM ALL WARRANTIES, EITHER EXPRESSED OR IMPLIED, INCLUDING BUT NOT LIMITED TO IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE, WITH RESPECT TO THE SOFTWARE AND ANY ACCOMPANYING WRITTEN MATERIALS OR HARDWARE.

IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY DAMAGES WHATSOEVER (INCLUDING, WITHOUT LIMITATION, DAMAGES FOR LOSS OF BUSINESS PROFITS, BUSINESS INTERRUPTION, LOSS OF BUSINESS INFORMATION, OR OTHER PECUNIARY LOSS) ARISING OUT OF THE USE OF OR INABILITY TO USE THIS PRODUCT, EVEN IF THE AUTHORS HAVE BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.

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Created: Jan 17 1996 --- Last modified: Fri Apr 26 21:12:00 1996