Existing CAD systems are still monolithic and are based on complex geometrical models. Our aim is to implement a new approach, taking advantage of the possibilities of the World Wide Web and providing a novice end-user with an easy-to-use system. In order to get the same performance as a local system, it is necessary to provide our system with an adequate data representation and architecture. A study realised by our team has shown that classical models are based on information that is too low-level for our specifications and that a functional model is needed. This paper deals with our first results concerning the architecture which is to be the basis of different implementations, and it presents a first operational prototype. The first section introduces the tests we carried out in order to understand the advantages and drawbacks of different alternatives, and it describes the final choices for the architecture. The second section describes a prototype proving the feasibility of our approach. It is based on new intuitive interaction techniques, though we merely outline this point in this paper.

Computer aided design now aims to provide designers with a support during the early stages of design. The purpose is to translate the client's specifications into a shape as automatically as possible. However, the processing of a text in natural language is still out of reach. We then assume that the client's specifications are manually translated into intermediate specifications composed of intermediate constraints upon physical parameters. Our efforts concern the transformation of these intermediate specifications into a shape, precisely the way to complete whether a shape satisfies the intermediate specifications or not. We first study the case in which the shape is a single primitive solid; we also give elements to choose the instance that best fits the specifications. Then, we study the extension of the method to solids defined by a combination of primitive solids.