Constraints for the web

Abstract

Constraints can be used to specify the desired layout of a web document, and also the behaviour of embedded applets. We present a system architecture in which both the author and the viewer can impose page layout constraints, some required and some preferential. The final appearance of the web page is thus the result of negotiation between author and viewer, where this negotiation is carried out by solving the set of required and preferential constraints imposed by both parties. We identify two plausible system architectures, based on different ways of dividing the work of constraint solving between web server and web client. Finally, we describe an implementation of a prototype constraintbased web authoring system and viewer, which also provides constraint-based embedded applets.