Wed, 8 Dec 93 10:39:21 -0500

We implemented interactive presentations in mosaic by adding
extensions to HTML similar to ones that have been suggested. Our point
of view was that mosaic needed to have interactive capabilities similar
to those available from commercial packages such as Macromedia
Director and Authorware. While we have not achieved that yet, I think
we have added some basic capabilities in that direction that bear
consideration by the WWW community.

I think the WWW community should debate carefully the desired "grand
scheme" in active presentations before implementing alot of little
pieces which may limit extensibility down the road. For a more
complete view of the needed capabilities, we should look more at what
Kaleida's Script-X, and similar scripting languages will do.

Some useful ideas:

Firstly, once you adopt the metaphor of active presentations you may
want to add the capability of controlling them. The ability to alter
the flow of presentation interactively adds greatly to the possible
applications. For example, tutoring. Our implementation acheived this
by loading in alternative augmented-html scripts depending on the
reply to a query.

We also added pause/continue buttons, forward/backward and play audio
buttons. This allowed us to browse through the presentation and
choose which segments to listen to. The display indicates page N of
TOTAL to let the user know where they are.

Secondly, the ability to alter the screen format is potentially
important. We added a <screenformat style#> command which altered the
mosaic window size, form factor, and display style. For example, Our
presentations used a mosaic window which covered the screen with a
backdrop so that the images could be viewed in an uncluttered
environment. The backdrop hid the normal mosaic document viewer
entirely. In other cases, we had images displayed on one side of the
terminal in conjunction with documents being displayed on the other.


Ira Smotroff
The MITRE Corporation