The Application Of Bayesian Network In Evaluation Index System Of Software Dependability

With the maturity of computer technology and rapid decrease of hardware cost, all kinds of computer systems which have complicated structures and powerful functions have been widely applied to security and key fields, like aerospace, transportation, nuclear resources and medical area. Human beings'life and wealth will suffer huge losses and environment will suffer severe damage if these systems fail. The dependability of system has increasingly become the focus. The configured software must have high dependability in view of the particularity of these systems. How to evaluate the dependability, especially quantified evaluation is a problem which deserves attention for internal of all kinds of software which become more complicated exists crisis, defects, fault and failure and external of software exist virus and intrusion of malicious code. But there is little research on this aspect.Bayesian network is graphics mode which is used to express the probability distribution of variable. It has stable mathematical basis and is suitable for express and analyze uncertain and probabilistic things. A model of software dependability evaluation index system based on Bayesian network is proposed in this paper. Compared to general probability analysis, it has obvious advantages in applicability of model, comprehensiveness of probability analysis and effective judgment to probable outcomes.The research on the following several aspects was developed in this paper:(1) It was discussed that the concept, related factors of software dependability and related problems of measurement of software dependability. The availability, reliability, maintainability are important factors which can influence the dependability of software. Measure standard of software dependability was analyzed according to characteristics of software dependability.(2) It was summarized that the related research results of software dependability evaluation model. The research on software dependability evaluation model was mainly divided into two modes: black box and white box. The main characteristic of these two modes was introduced and the problems exist and to be solved were also analyzed.(3) It was discussed that the origin, development and concept of Bayesian network. It was analyzed that the characteristic of Bayesian network and its probability and advantages applied to software dependability evaluation. (4) It was discussed that the characteristic and requirement of software dependability evaluation model. A novel evaluation model of software dependability was proposed based on Bayesian network. In this model, the related factors of software dependability are as measurement metric, the system structure is as evaluation system, Bayesian network is as expression system and requirement specification of dependability is as basis of evaluation. It was proposed that a dependability evaluation method based on dependability of requirement specification.(5) The dependability model is applied for the dependability evaluation of a telecom application, based on the software test results and evaluation of software quality and software capability.