Distributed communication software specification based on the action superposition mechanism

A mechanism for specifying distributed communication software is proposed. Using this mechanism, each process is specified by three types of constraints: an event to a process is decomposed into event elements and distributed to relevant processes in accordance with decomposing constraints; each process independently performs actions by its functional constraints; and the output is determined by superposing constraints as a superposing result of each process action. Because the functional constraints are independent of other processes, they can be made up of reusable components. To facilitate specifying the decomposing and superposing constraints, a language based on constraint-oriented logic programming is developed. The authors also propose a constraint evaluation system which executes reasoning rules to obtain outputs from input events and knowledge of constraints. The bound/unbound concept of event variables is employed to implement the execution control of each constraint evaluator. Using plain old telephony service and call waiting service as examples, the advantages of the mechanism and the evaluation system are shown.<>