A model driven framework for N-version programming

Complex systems-of-systems (SoS) requiring fault-tolerance and high reliability often require redundant systems. The concept of redundancy that includes components with differing failure modes is well understood in the realm of hardware design. N-version programming, although shown to produce significant gains in software reliability over single-version fault tolerant techniques, is not widely accepted or applied. This is due, in part, to N-version programming's lengthy development time and its inherent problems with version independence. Model Driven Software Development (MDSD) is a process that promises gains in software productivity and quality. While progress in MDSD has witnessed the expansion of the supporting Unified Modeling Language profile for modeling fault tolerant characteristics, and the development of specific design patterns for the production of fault tolerant software, MDSD's support in the generation and testing of fault tolerant applications is not evident or explicitly defined. This paper discusses the development of a fault tolerant MDSD framework, which enables users to design, implement and test fault tolerant applications using the N-version modeling technique. The framework closes the gap between existing modeling patterns and the practical application of fault tolerant MDSD, and supports follow-on research to address specific questions relating to the benefits of MDSD within the fault tolerance software domain.