Fault contribution trees for product families

Software fault tree analysis (SFTA) provides a structured way to reason about the safety or reliability of a software system. As such, SFTA is widely used in mission-critical applications to investigate contributing causes to possible hazards or failures. In this paper we propose an approach similar to SFTA for product families. The contribution of the paper is to define a top-down, tree-based analysis technique, the fault contribution tree analysis (FCTA), that operates on the results of a product-family domain analysis and to describe a method by which the FCTA of a product family can serve as a reusable asset in the building of new members of the family. Specifically, we describe both the construction of the fault contribution tree for a product family (domain engineering) and the reuse of the appropriately pruned fault contribution tree for the analysis of a new member of the product family (application engineering). The paper describes several challenges to this approach, including evolution of the product family, handling of subfamilies, and distinguishing the limits of safe reuse of the FCTA, and suggests partial solutions to these issues as well as directions for future work. The paper illustrates the techniques with examples from applications to two product families.