Abstract
This paper proposes a novel heterogeneous software architecture GFTSA (Generic Fault Tolerant Software Architecture) which can guide the development of safety critical distributed systems. GFTSA incorporates an idealized fault tolerant component concept, and coordinated error recovery mechanism in the early system design phase. It can be reused in the high level model design of specific safety critical distributed systems with reliability requirements. To provide precise common idioms & patterns for the system designers, formal language Object-Z is used to specify GFTSA. Formal proofs based on Object-Z reasoning rules are constructed to demonstrate that the proposed GFTSA model can preserve significant fault tolerant properties. The inheritance & instantiation mechanisms of Object-Z can contribute to the customization of the GFTSA formal model. By analyzing the customization process, we also present a template of GFTSA, expressed in x-frames using the XVCL (XML-based Variant Configuration Language) methodology to make the customization process more direct & automatic. We use an LDAS (Line Direction Agreement System) case study to illustrate that GFTSA can guide the development of specific safety critical distributed systems.