Specification-Driven Prototyping for Architecting Dependability

This paper describes a major part of an architecting methodology developed for safety-critical fault-tolerant software systems. The methodology coverage centers on specificationdriven prototyping. This approach to prototyping is seen to be superior to the customary approaches of throwaway and evolutionary prototyping. A still developmental form of representation, higher-level statecharts, provides a suitably expressive prototype specification language. Dependability is held to rely crucially on the rigor and specificity of the architecting process, as well as on the propagatability of its products. The subject four-step prototyping approach can subserve such needs, especially with regard to conceptualization insights, complexity management, dynamic analysis, and dependability assurances. Such efforts primarily address the underlying architecture or infrastructure of a nascent software system. In particular, the advocated prototyping approach focuses on absolute time-based concurrency, with accommodation of arbitrary scalability, non-ideal timing, and stochastic effects.