Integrating variability and safety analysis models using commercial UML-based tools

Software and System Product Lines (SSPL) are the state-of-the-art for systematically reusing a common set of core assets in the development of similar products in a product family. A large number of SSPL success stories have been published in the last decade and commercial tool support is also available. SSPLs promise to reduce cost, to shorten time-to-market for new features, and to increase product quality by systematically reusing core assets in the development of three or more systems. However, an open challenge is SSPL engineering for safety-relevant systems such as automotive, avionic, or industrial automation systems. Safety-relevant systems have to be developed, analyzed, and certified according to safety standards such as IEC 61508. These standards demand the application of safety analyses such as Fault Tree Analysis and Failure Mode and Effect Analysis. Starting the safety analysis of each product variant of a SSPL from scratch is complex and very time-consuming. However, there are only few convincing cases, where SSPL approaches have been followed in safety engineering. To pave the way for a broader adoption of SSPL approaches, this paper reports practical experiences with industrial-strength methods and tools along an adaptive cruise control SSPL. The paper demonstrates how commercial tools can be used (i) to analyze safety-related aspects already in the architectural design, (ii) to model the results as component integrated component fault trees (C2FT), and (iii) to systematically reuse C2FT in the safety analysis of a concrete product. The results of the case study show that C2FT (i) can be easily integrated into a feature-oriented development process of SSPL, (ii) facilitate early consideration of safety in domain engineering, and (iii) reduce effort and complexity of safety analyses in application engineering.