Software fault trees and software failure modes and effects approaches for reliminary phases of object oriented software design

Abstract

Software plays a dominant role in safety-critical applications to control and monitor their newlinecritical activities. Software safety encapsulates the aspects of software engineering and newlinesoftware assurance that provide a systematic approach to identifying, analyzing, tracking, newlinemitigating, and controlling hazards and hazardous functions of a system where software newlinemay contribute either to the hazard or to its mitigation or control, to ensure safe newlineoperation of the system (NASA-STD-8719.13C, 2013). The role of software safety is to newlinemake sure that software operates within the defined system context and may not cause newlineany unacceptable risk. Software safety analysis is the process of first identifying the newlinepotential hazardous states of the system and then providing the mitigation means for the newlinesources of the identified hazards. Two software safety approaches namely Software Fault newlineTree Analysis (SFTA) (Leveson, 1983a)and Software Failure Modes and Effects newlineAnalysis (SFMEA) (Reifer, 1979) are the recommended approaches (NASA-GB- newline8719.13, 2004) for the analysis of software-induced hazards in the system. SFTA is newlineadapted in software domain by borrowing the features of a hardware safety approach newlinenamely Fault Tree Analysis (FTA) (Vesely et al, 1981). Similarly, Software Failure newlineModes and Effects Analysis (SFMEA) approach is adapted for software by borrowing newlinethe features of one another hardware, safety approach, namely Failure Modes and Effects newlineAnalysis (FMEA) (MIL-STD-1629A, 1980). newlineSFTA is a deductive, backward (or top-down) safety analysis approach to the analysis of newlinesoftware induced critical hazards in the system. SFTA approach is backward or top-down newlinein nature because its application starts by first identifying the critical hazardous-state that newlinea system can encounter and then identifying the erroneous events responsible for the newlineoccurrence of the identified hazard-state. On the other hand, SFMEA is inductive, newlineforward (or bottom-up) software safety analysis approach and its application first newlineidentifies the basic software-related.