Eliciting additional safety requirements from use cases using SFTA

Use case based approaches for software requirement analysis have been used extensively in software development industry to capture functional and behavioral requirements. But use-case based techniques for requirement analysis has not been found to be much effective and supportive enough for capturing non-functional requirements such as safety requirements. To overcome this problem, a systematic approach for eliciting additional and or missing safety requirements from textual description of use cases by the manual application of a well known software safety analysis (SSA) technique named Software Fault Tree Analysis (SFTA) has been proposed and presented in this paper. SFTA has been derived and applied in software from a similar hardware safety analysis technique named Fault Tree Analysis (FTA). The technique presented in this paper operates with the assumption that textual description of the use cases is correct. The effectiveness of the proposed approach has been demonstrated via an application of SFTA on the use case model (UCM) for an Elevator Control application.