Acknowledgements
The load on a system that runs an http server with spawned application processes should remain reasonable, unless hundreds or thousands of users try to run applications on the same server at the same time. If such a success were to happen, it would be quite easy to limit the number of applications that the server would accept to run at the same time.
If this kind of use of the web increases in scale, it might prove useful to revise the http protocol and extend it to better support such use. Among the extensions that could be considered, there is the incremental modification of displayed documents to reduce network load, and the support for multi-part documents, that is, documents that contain various parts that require different viewers. For instance a document could consist of an HTML part, accompanied by a sound file that could be played at the same time the user is reading the HTML part.
It might also prove useful to extend the mark-up language to include some simple clickable image support on the client side. For instance, the inline image tag (<img ...>) could include a list of rectangle-href pairs that would allow the viewer to directly send a request for the document mentioned in the href part whenever the user clicks in the area of the image defined by the rectangle part. This would make it much easier for information providers to include clickable images in their documents without having to embed its handling in the server configuration.
As for security issues, the scheme that has been described in this paper should not create any security breach on either the client or the server side, since the client only sees HTML documents and the server only executes applications that are local to the server and can thus be trusted.
The last point that we want to mention is that pedagogical aspects of such use of the web have not been discussed here since we have not had the opportunity yet to try the system with students. This kind of computer aided learning does not pretend to be as effective as mastery learning programs that run on standalone machines since delivering educational material through the web reduces somewhat the capabilities that can be used. Even in the face of its limitations, the World Wide Web provides a very interesting alternative when it comes to distance learning, and our project is there to prove it.
Acknowledgements