A constructive approach to the design of distributed systems

The underlying model of distributed systems is that of loosely coupled components running in parallel and communicating by message passing. Description, construction and evolution of these systems is facilitated by separating the system structure, as a set of components and their interconnections, from the functional description of individual component behaviour. The Conic environment for distributed programming supports this model. In particular, Conic provides a separate configuration language for the description, construction and evolution of distributed systems. The Conic environment has demonstrated a working environment which supports system distribution, reconfiguration and extension. The principles of explicit system structure and context independent components that underlie Conic have lead naturally to a design approach which differs from that of both current industrial practice and current research. Its approach is termed `constructive´ since it emphasises the satisfaction of system requirements by composition of components. The authors describe the approach and illustrate its use by application to an example, a model airport shuttle system which has been implemented in Conic