Research On Web Service Selection And Supplier Assignment Problems

The software development methods based on Service-oriented Architecture(SOA)stand out and arouse wide concern among the software industry and academic circles.Web(World Wide Web)services,as a kind of technology applied in distributed computing,are now regarded as a major implementation of services in SOA.The Web services-based software development methods under SOA are mainly divided into two types,namely composition and selection of Web services and supplier involvement in development.Through composition and selection of Web services,the best services can be selected from numerous web services to constitute high-quality software products.Through supplier involvement in development,companies can utilize the expertise of their suppliers to participate in the design of software products and provide specific software products.Since no uniform and stringent scales have been used to measure various attributes of Web services in software engineering,it is impossible to solve the problems in selecting Web services simply by means of the methods that the manufacturing industry adopts to select standard components.Moreover,in the Web services-based software development projects,many constraints,such as task assignment of Web services providers in uncertain environments and selection of Web services based on QoS(Quality of Service)attribute constraints,shall be considered for selection of Web services and task assignment of suppliers involved in development.Therefore,the research on selection of Web services and task assignment of suppliers has great theoretical and engineering significance.Nowadays,Web services-based software development is mostly studied from the perspective of computer science and technology.Operations research and management science are more appropriate perspectives for investigating the selection of Web services and task assignment of suppliers involved in development.Mathematical theories and methods can be used to objectively describe user requirements,QoS attributes(e.g.reliability and availability)and various characteristics of suppliers(interoperability and development cycle).Based on the quantitative descriptions,decision models and methods can be established to provide decision services for software engineering managers.By taking the train of thought above as the way of research and the software development of Web services as the background,several problems in selection of Web services and task assignment of suppliers were investigated in depth in accordance with the theories and methods of system engineering.(1)The value of QoS attributes and the uncertainty of user preferences were investigated.Intuitionistic fuzzy sets were used to objectively describe user preferences and QoS attribute value.On this basis,the VIKOR and GRA methods were combin ed.An intuitionistic fuzzy multi-attribute method based on VIKOR-GRA was proposed for selection of Web services.Based on the instances in selection of Web services,sensitivity analysis and comparison with the intuitionistic fuzzy TOPSIS-GRA method,the proposed method was verified and proven to have better stability,validity and degrees of differentiation.(2)The composition and selection of Web services based on workflow were investigated.When applied to solve the optimization problem in composition and selection of Web services,traditional intelligent algorithms have low optimizing capability and stability and can easily fall into local optimum,thus resulting in premature problems.Therefore,an improved fireworks algorithm was proposed.The gray relative analysis method was used to improve the selection strategy of fireworks algorithm.Meanwhile,to improve the algorithm's capabilities in local mining and global mining,the strategies for Gaussian mutation and Cauchy mutation were combined to form a mixed mutation operator.The neighborhood structure was also introduced into the mixed mutation operator,so as to improve the algorithm's performance in local search(3)The selection of Web services based on user requirements was investigated.Given that traditional QFD does not adequately consider user satisfaction and competitiveness of requirements in determining the weight of QoS attributes,a new method was proposed to determine the weight of QoS attributes comprehensively based on QFD-IFS,Kano model and information entropy.The QFD-IFS method was used to convert the user requirements into QoS attributes,and calculate the basic weight value of QoS attributes.The Kano model was introduced to determine the user satisfaction index,improve basic weight value,and finally obtain the weight value of user satisfaction.In view of the actual performance of user requirements in the enterprise,information entropy was used to calculate the competitive correction factor of QoS attributes.The weight value of user satisfaction was improved from the competitive relationship of requirements.As a result,the accuracy and objectivity of user requirements analysis were finally improved.(4)The development capabilities,cost,time and synergic relationship of suppliers and the uncertainties of Web services-related information were investigated.A fuzzy model of task assignment was proposed for Web service providers in collaborative development environment.Language was adjusted to quantify the coefficient of OWA operator and regulate the weight coefficient of index in accordance with the degree of user preference.The complex fuzzy multi-objective optimization problem was reduced to a simpler single-objective optimization problem.With the proposed method,it will take the shortest time for suppliers to provide the best Web service performance at the lowest cost in collaborative development environment.