Research On QoS-based Web Service Selection And Exception Handling Method For Cloud Environment

In recent years, Cloud computing platform has become a hot topic which is attracting more and more attention both in industries and academics, and the number of Web services available on the Cloud environment has expanded dramatically. Through service composition, multiple interoperable and heterogeneous Web services could be composed into a more powerful value-added service, so as to satisfy the diversified and personalized requirements of Cloud environment. Currently, Cloud computing platform brings new rapid development for Web service composition technology, at the same time several problems and challenges are present in QoS-aware Web service composition, which are mainly specified as follows:How to process the service selection of QoS optimization under the premise of ensuring to meet the constraints of atomic services. How to deal with the service composition execution exception caused by Web service failure, so as to ensure the reliability of the service composition reliability in such a heterogeneous platform of cloud environment.To solve these challenges based on previous work, this paper presents sophisticated discusses of issues about Web service selection and the exception handling in this process and arrives at phased achievements.Considering the characteristic of the atomic services supplied by service providers in cloud environment are not segregate and irrelevant with each other, the QoS-aware service selection method proposed in this paper is based on building the service composition tree which considers sufficiently of constraints between atomic services. Then seek a QoS optimal Web service composite solution. In addition, the pruning strategy is used to improve the efficiency of service selection process. At last, multiple sets of experimental verification have proved the validity of this method in solving the service selection problem in cloud environment.Besides, a context-oriented exception handling method is proposed to solve the service node failure of composite service in cloud environment. Firstly we find the starting service nodes which is need to be replaced, and then choose the different ways include value-priority strategy and cost-priority strategy according to the different positions of the failure service node. By evaluating the two different methods, the user can choose the optimal treatment strategy which will help to obtain the optimal service experience. At last, an experiment is presented for validating the performance and the reliability of the exception handling method based on the composite services.