Designing distributed programs with dynamic communication structures

The growing interest in using clusters of workstations as the target platform for high-performance applications, has again emphasized the need for support tools that can be used during application design. In this paper we present a graphical technique, called ADL-D, that allows a developer to construct an application in terms of communicating processes. The technique distinguishes itself from others by its use of highly orthogonal concepts, and the support for automated code generation. Developers are encouraged to concentrate on designing components in isolation, making the complex design space more manageable than would otherwise be the case. ADL-D can be used from the early phases of application design through phases that concentrate on algorithmic design, and final implementation on some target platform. Rather than presenting details of ADL-D, we use it here as a vehicle for a more general discussion on design level support for parallel and distributed applications. In this discussion, an emphasis is put on the design of dynamic communication structure, i.e. structures that can change during runtime.