Software Reliability Case Development Method Based on the 4+1 Principles

For high reliability software, mission-critical software and embedded system software, convincingly and validly proving that the software meets reliability requirements is one of the most challenging issues. Traditional reliability cases are developed by decomposing reliability into several sub properties and focusing on whether these properties are satisfied. In this paper, we propose the "4+1" principles of software reliability from the perspective of software-related anomalies being handled by reliability requirements. The introduction of reliability requirements in 4+1 principles not only provides a solid foundation for claims in reliability cases but also avoids introducing defects during the development process. In addition, this paper proposes a reliability case development method based on 4+1 principles, taking into consideration whether software has correctly handled software-related anomalies and reliability requirements designed into the software. Based on the above method, the general argument patterns for software reliability cases are proposed. As a case study, we have taken load control software to demonstrate how a software reliability case can be generated using the proposed method and corresponding argument patterns.