An internet based architecture satisfying the distributed building site metaphor

Virtual reality offers new possibilities of cooperation for the concept phase of a product development. The deployment of a cooperative system suffers mainly from the client-server approach that is inefficient in many ways and attributes a leading role to a server site. Moreover, requiring a specific quality from the under-laying communication restricts openness and usability of the solution. At last, current solutions focus on reliable multicasting and manage moving objects but they address poorly consistency and parallel working. The paper describes the Distributed Building Site Metaphor. That solution enables a real-time 3D cooperative design and parallel work within shared virtual worlds while preserving the scene consistency. Designers move easily between different styles of work. They prepare the shared work on a standalone basis. During a meeting, the shared work reforms automatically. The participants move from a collaborative design to a review activity or real-time conciliation. The main focus is the core services and protocols supporting efficiently the different properties of our metaphor. Communication services over standard IPv4 or IPv6 protocols are proposed. They use intensively the multicast ability of IP protocols and support a fully distributed approach without any centralized control.