Towards Formal Safety Analysis in Feature-Oriented Product Line Development

Abstract

Feature-orientation has proven beneficial in the development of software product lines. We investigate formal safety analysis and verification for product lines of software-intensive embedded systems. We show how to uniformly augment a feature-oriented, model-based design approach with the specification of safety requirements, failure models and fault injection. Therefore we analyze system hazards and identify the causes, i.e. failures and inadequate control systematically. As features are the main concept of functional decomposition in the product line approach, features also direct the safety analysis and the specification of system level safety requirements: Safety design constraints are allocated to features. Subsequently, the behavior including possible faults is formally modeled. Then formal verification techniques are employed in order to prove that the safety constraints are satisfied and the system level hazards are prevented. We demonstrate our method using Scade Suite for the model-based product line design of cardiac pacemakers. VIATRA is employed for the model graph transformation generating the individual products. Formal safety analysis is performed by using Scade Design Verifier. The case study shows that our approach leads to a fine-grained safety analysis and is capable of uncovering unwanted feature interactions.