Virtual reality systems provide realistic look and feel by seamlessly integrating three-dimensional input and output devices. One software architecture approach to constructing such systems is to distributethe application between a computation-intensive simulator back-end and a graphics-intensive viewer front-end which implements user interaction. Inthis paper we discuss Metis, a toolkit we have been developing based on such a software architecture, which can be used for building interactiveimmersive virtual reality systems with computationally intense components. The Metis toolkit defines an application programming interface on thesimulator side, which communicates via a network with a standalone viewer program that handles all immersive display and interactivity. Networkbandwidth and interaction latency are minimized, by use of constraint network on the viewer side that declaratively defines much of dynamic andinteractive behavior of the application.
