Stepwise Refinement of Communications Service Specifications for Conforming to a Functional Model

Akira TAKURA  Tadashi OHTA  

IEICE TRANSACTIONS on Communications   Vol.E77-B   No.11   pp.1322-1331
Publication Date: 1994/11/25
Online ISSN: 
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Issue on Distributed Architecture for Next Generation Communication Networks)
stepwise refinement,  communications networks and services,  functional model,  service specification,  protocol synthesis,  communications software,  

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A stepwise refinement method of communications service specifications is proposed to generate communications software that can conform to any network architecture. This method uses a two-layered language; one layer is a service specification description language (STR), and the other layer is a supplementary specification description language for implementing STR description on a communications system (STR/D). STR specifies terminal behaviors that can be recognized from a perspective outside of the communications systems. With STR, a communications service is defined by a set of rules that can be described without detailed knowledge of communications systems or communications network architectures. Each STR rule describes a global state transition of terminals. Supplementary specifications, such as terminal control and network control, are needed to implement communications services specified by STR rules. These supplementary specifications are described by STR/D rules. Communications services, such as UPT (Universal Personal Telecommunication), are standardized so that they can be provided on a given functional model consisting of functional entities. Specifications for each functional entity in a network are obtained from the two kinds of initially described specifications mentioned above. The obtained specifications are described by STR(L) and STR/D(L) rules, which specify local specifications of a functional entity. These specifications for functional entities are then transformed into software specifications, and finally communications software is generated from these software specifications. This stepwise refinement method makes it possible to generate communications software that can conform to any functional model from service specifications.