A Scenario-based Approach; Assuring Effect of Software Product

Abstract We provide an operational scenario-based assurance method for assuring the safety of a software product. Software safety is usually demonstrated by assessing the software development process in what is called a process-based approach. Because the process-based approach indirectly explains safety of software product, it cannot explicate safety boundary: Software product is safe or unsafe in what context of use. In this paper, we focus on operational scenario and unusual events which can occur in the scenario. The proposed method provides an operational scenario-based safety case which explains tolerable and not-tolerable abnormal scenarios including unusual events as the boundary. The method promotes domain experts identifying unusual events from a normal scenario. Furthermore, it constructs scenario-based safety case by using Event Sequence Diagram. To evaluate the method, we applied it to a ground system for artificial satellite, and engine control system of the rocket system. As a result, we conclude that the method can construct a valid operational scenario-based safety case.