Variability evolution and erosion in industrial product lines - a case study

Successful software products evolve continuously to meet the changing stakeholder requirements. For software product lines, modifying variability is an additional challenge that must be carefully tackled during the evolution of the product line. This bears considerable challenges for industry as understanding on how variability realizations advance over time is not trivial. Moreover, it may lead to an erosion of variability, which needs an investigation of techniques on how to identify the variability erosion in practice, especially in the source code. To address various erosion symptoms, we have investigated the evolution of a large-scale industrial product line over a period of four years. Along improvement goals, we have researched a set of appropriate metrics and measurement approaches in a goal-oriented way, applied them in this case study with tool support, and interpreted the results including identified erosion symptoms.