A Method to Formally Evaluate Safety Case Evidences against a System Architecture Model

Abstract

For a large and complex safety-critical system, where safety is ensured by a strict control over many properties, the safety information is structured into a safety case. As a small change to the system design may potentially affect a large section of the safety argumentation, a systematic method for evaluating the impact of system changes on the safety argumentation would be valuable. We have chosen two of the most common notations: the Goal Structuring Notation (GSN) for the safety argumentation and the Architecture Analysis and Design Language (AADL) for the system architecture model. In this paper, we address the problem of impact analysis by introducing the GSN and AADL Graph Evaluation (GAGE) method that maps safety argumentation structure against system architecture, which is also a prerequisite for successful composition of modular safety cases.In order to validate the method, we have implemented the GAGE tool that supports the mapping between the GSN and AADL notations and highlight changes in impact on the argumentation.