Research On Software Trustworthiness Evaluation Model And Its Optimization

With the fast advance in information technology (IT), software has become indispensable tomodern manufacturing and services in which the operational behavior of the software has a directimpact on the product performance and the service quality. Unfortunately, software systems arenot always trustworthy---bugs and unhandled exceptions may cause software behavior to deviatedramatically from the user's expectation. Therefore, there is an increasing demand for evaluatingsoftware trustworthiness to reduce the social security problems and the tremendous economiclosses caused by untrustworthy software.The current STE models focus on the quantitative evaluation of trustworthiness through theuse of software metrics or logic verification method. While these models successfully solved a lotof actual problems, they are facing three major challenges for complex software systems:(1) Theusers' subjective trustworthiness requirements are neglected in practice;(2) The key fatorsimpacting trustworthiness evaluation are ignored in the models construction;(3) The traditionalmodels fail to have the dynamic adaptability. The dissertation systematically studies theconstruction of trustworthiness evaluation indicator system, the objective weighting, theevaluation model establishment and its optimization, and software recommendation consideringseveral trustworthy attributes. A great number of numerical experiments demonstrate theeffectiveness and applicability of the proposed models and algorithms.The main contributions of the dissertation are summarized as follows.(1) The universal software trustworthiness evaluation process is studied. Based on theanalysis of the key scientific issues in the software trustworthiness evaluation, a dynamicconstruction model of trustworthiness evaluation indicator system and a finite state model oftrustworthiness evaluation application are developed.(2) For the trustworthiness evaluation problem with a variety type of uncertainties, a softwaretrustworthiness evaluation model is developed by using the evidential reasoning approach and theutility theory. For the sake of multi-dimension evaluation information pre-processing, amultisource-heterogeneous trustworthiness evidences conversion and consistent constructionmethod is proposed. To enhance the accuracy and objectivity of the evaluation, a new objectiveweighting approach based on the total uncertainty measure is discussed. On this basis, atrustworthiness evaluation reasoning model, which can analyze and solve uncertainly softwaretrustworthiness evaluation problem, is given based on the distributed evaluation framework.Numerical experiments show that the proposed model is suitable to large-scaled industrial detection software characterized by multiple trustworthy attributes and uncertainty trustworthinessevidences.(3) For the trustworthiness evaluation problem characterized by unreliable evidences, twodiscounting-factor estimation methods are discussed for objective and subjective evidences,respectively. As for the evidences collection cases of expert scoring or software probability modelforecasting, a joint coefficient integrating discounting factor with relevance weight is defined forthe unreliable evidences pretreatment. In addition, an extended ER approach applying the jointcoefficient is proposed. The experimental analysis shows that the proposed discounting methodsare not only suitable for the unreliable evidences pretreatment but also for trustworthinessevaluation model enhancement.(4) For the trustworthiness evaluation problem with non-independent evidences, an improvedDenoeux cautious conjunctive rule and a horizontal evidence combination algorithm areintrouduced. On the analysis of objective problems, such as information uncertainty andcorrelation of information sources in the process of evaluation, a software trustworthinessevaluation reasoning algorithm is developed. The experimental analysis shows that the proposedtwo algorithms are suitable to solve the trustworthiness evaluation problem with non-independentevidences, and the accuracy of the trustworthiness evaluation model has improved.(5) For the trustworthiness dynamic evaluation and trustworthy software recommendationunder the software evolution, the incidence matrix is used to make correlation analysis betweentrustworthy attributes and then the variation rule of relative weight is revealed. An adaptive systemof reconstruction device, which can analyze and sovle the software trustworthiness evaluationindicator system of self-reconfiguration, is designed based on the incidence matrix. A completeframework of trustworthiness evaluation and evoluation model is proposed. On this basis, thetrustworthy attributes have been integrated with software service selction in Cloud Computing. Anovel cloud recommendation system (CRS) supporting software with various specified functionaland QoS guarantees such that the CRS can mediate multi-attribute matching between solutionsand consumer's demands is designed.