Research On Relationship And Transition Between The Software Reliability And Safety

As software has been widely used in advanced technology fields (like 211 space program in our country), software reliability and safety has been more and more concerned by people. In many types of systems, such as flight control system, air-control system, security monitoring system in nuclear power plant, tragacanth control system, communication system, pacemaker and so on, software has been the main factor in achieving their functions. Therefore, researches on this theory and application of software reliability and safety plays an important role in developing advanced technology ,also in relation to national security, military security , scientific and technical innovation , and popularization and application of great products.In the past researches, people separated software reliability and safety and had done a lot of researches from different point of view. Their research achievements mainly concentrated on the principles, methods and technologies of oftware reliability and safety. However, there is not enough attention paid in the relationship and integrated application. Even some problems of vague concepts and confused use methods exist. It had a strong impact on comprehensive assessment, evaluation and accident survey of software reliability and safety and causes comparatively large restriction in theory research and project application.This article begins with the research on relationship of software reliability and safety, and sets up axiomatic system on the uniform of software reliability and safety. It provides clear relationship of software reliability and safety, proposes a transition rule between them in certain conditions and illustrates the application in practice of their relationship and transition rule. Not only does the article enrich the theoretical basis of software reliability and safety, but also provides technology guarantee on comprehensive application of software reliability and safety.The main contributions and innovations in this article are listed below:1 Establish axiomatic system on the uniform of software reliability and safety, lay a good foundation for formal research of software reliability and safety..By analysis of basic concepts of software reliability and safety, analysis of the connotation of them,findings of mutual essential distinction and redefinition of some vague concepts, it establishes uniform symbolic system and axiomatic system.The established axiomatic system makes a good foundation of formal description and formal provement.2 Propose relationship between software reliability and safety, and prove it by formal approach.There are different opinions from different scholars. It is hard to judge which one is correct before establishment of uniform formal descriptive method. Using uniform axiomatic system's description, it can clearly differentiate the relationship between them so that solve the problem of vague in mutual relationship between them and related debate.3 Raise transition rule in certain conditions between software reliability and safety, provide theoretical guarantee for comprehensive application of reliability and safety. At the present time, there exist a lot of repetitive work in analysis of software reliability and safety which increase the software development cost.How to reduce repetitive work meanwhile not to influence the analysis results is one of the main problems which need to solve in comprehensive application of software reliability and safety, and transition rule between software reliability and safety provides a theoretical guarantee for solving this problem.4 Utilize the relationship between software reliability and safety, put measure means in reliability into measurement in safety, lay a foundation for quantification of software safety work. Research on safety measurement has always been one of the main parts in safety research where there exists a qualification models for hardware safety measurement while software safety measurement is a weak link. Combining the measure means in software reliability with safety measurement by mutual relationship between reliability and safety lays foundation for the safety measurement.5 Provide the application of transition rule in FTA approach; unite the theoretical method and actual application. The application value of transition rule is mainly reducing the repeated work and judgement of accidental responsibility in engineering practice. FTA approach is a common method in analysis of software reliability and safety, and it is easy to see the effect of transition rule in reducing the repeated work and judging of accidental responsibility by combing transition rule with FTA.