Stochastic software safety/reliability measurement and its application

Abstract

Safety and reliability have become important software quality characteristics in the development of safetydcritical software systems. However, there are so far no quantitative methods for assessing a safetydcritical software system in terms of the safety/reliability characteristics. The metrics of software safety is defined as the probability that conditions that can lead to hazards do not occur. In this paper, we propose two stochastic models for software safety/reliability assessment: the dataddomain dependent safety assessment model and the availabilitydrelated safety assessment model. These models focus on describing the timed or executionddependent behavior of the software faults which can lead to unsafe states when they cause software failures. The application of one of these models to optimal software release problems is also discussed. Finally, numerical examples are illustrated for quantitative software safety assessment and optimal software release policies.