The Theory And Application Of A Growth Model Of Software Reliability And Safety

As early as in the 1960s software crisis initial period, along with software function's growth, the people realized that is high to the software order of complexity, the development cycle is long, the reliability is bad, development and maintenance cost big and so on questions. And the reliability bad is the concentrated expression of software quality question, but the software quality bad is also one of software maintenance expense big primary factors. Thus it can be seen, the software quality question is long-standing.Informationizes day by day along with the society, society's daily movement relies on more and more software's electronic system; the widespread application of Software in state-of-art domain (such as flight control system, nuclear power station safe monitoring, drugs manufacture control system and so on) has manifested software's importance, but simultaneously software's massive applications also caused the accident which caused by the software disaster to be getting more and more, these accident's harm was very serious, the close relation people life and property and ecological environment's safety, this has only then slept lightly the people in near 10-20 years to software's reliable value as well as to the software safety research. Software's quality is very important for system's normal work and safe, moreover software whether could trust already became the state economy and the national defense and so on one of system whether normal work key aspects. How to appraise and safeguard these software's reliability and the safety, particularly the safety, prevents the disaster accident's appearance, already became the major issue which urgently awaits to be solved.Wu Zhi(Wu Zhi, 2005) when constructs software peaceful the entire model not only considered the unsafe output which are examined by the examining personnel but also considered the insecurely outputs which is impossible examined by the examining personnel.For ease of analysis processing, this article constructs the software safety model which is only considered the unsafe output which is possibly examined the personnel. This article the order which increases progressively according to the software disaster importance the software disaster divides into the limited h kind, through inspecting the mutual influence relations between the software disaster, a new software reliability and the secure appraisal model based on the sub-Markov chain is constructed.Finally, using the method of the graph, the comparison of fit and unfit quality are carring on between the existing models and this model by the concrete data in the theory .Through the contrast, we discovered: (1)the software reliability estimates of modelling haggles over lowly; (2) speaking of has the high important failure, the modelling software safety estimates haggles over lowly, but when time software testing close conclusion is actually high. (3)looking from plans with the goodness of fit (expectation accumulation breakdown number and actual accumulation breakdown number planning with) the angle, the software safety estimate of the modelling is more precise than that of the existing models.The quantification methods of the software reliability and safety are innovated in This article, this provides one new theory method. for the project personnel to the analysis and design and appraisal and forecast of software system's reliability and safety.