DARBS: A Distributed Blackboard System

Prior to this work, an algorithmic and rule-based blackboard system (ARBS) had been developed over a ten-year period. ARBS benefited from a versatile rule structure and the ability to mix computational styles either as separate knowledgesources or by embedding algorithms within rules. It was a serial system – any knowledge source that was able to contribute had to wait its turn. We report here on a new distributed system, DARBS, in which the knowledge sources are parallel processes. Based around the client/server model, DARBS comprises a centralised database server, i.e. the blackboard, and a number of knowledge source clients. As the clients are separate processes, possibly on separate networked computers, they can contribute to the solution of a problem whenever they have a contribution to make. DARBS therefore achieves the well-established but elusive ideal of opportunism. It behaves as a distributed agent-based system, with the proviso that all communication is via the blackboard. DARBS is currently being applied to automatic interpretation of nondestructive evaluation (NDE) data and control of plasma deposition processes.