Integration Problems in Telephone Feature Requirements

The feature interaction problem is prominent in telephone service development. Through a number of case studies, we have discovered that no single semantic framework is suitable for the synthesis and analysis of formal feature requirements models, and the choice of modelling language has certain knock-on effects on the transformational design steps which lead to implementation. We initially describe a mixed semantic model approach whilst acknowledging that integration is a major concern. Our method incorporates operational state transition models, temporal logic formulae and object oriented structuring mechanisms. Each of these approaches gives rise to certain advantages and disadvantages, and we propose a complementary integration which allows the client to express their requirements in the way in which they understand their needs, whilst building formal models for transformation and verification during design. This paper evaluates such a mixed semantic approach in the domain of telephone feature development. It motivates the need for a single formal language which provides a unified semantic framework and incorporates all of the desirable properties of each of the semantic models used in the mixed semantic approach. We propose the hidden algebraic approach as providing just such a suitable semantic framework.