Research On Reliability Analysis Of Web Service Composition Based On BPEL

With the rapid development of information technology,the Internet has gradually become an open distributed computing environment,and the continuous development of Web service technology makes Web services become the mainstream choice of service technology.More and more enterprises want to build distributed systems by dynamically combining different services provided by various service providers in service-oriented research.The quality of service(Quality of services,Qo S)is the focus of Web services portfolio evaluation,so how to dynamically and efficiently analyze the service quality of Web service portfolio,such as reliability,is a hot issue worth discussing.At present,domestic and foreign scholars have done a lot of research on the reliability of Web services portfolio,although have also achieved certain research results,but it is still in its infancy.Based on the achievements of previous generations,this thesis mainly studies the following work:1.Based on the analysis of the traditional software reliability model and calculation method,combining the similarities and differences between the Web service composition and the traditional software,this paper studies the reference significance of the traditional software reliability study for the reliability research of the Web service composition system,and studies the existing Web Services Composition Reliability Evaluation Method.2.For the problem of low accuracy in the evaluation of Web service composition reliability,this paper proposes an improved model based on the granularity of BPEL activity structure considering the reliability factors of the combined conditions.The relationship between the reliability performance of Web service composition and the combination structure of Web services and the combination of service conditions is studied.Based on the connection structure between BPEL structured activities and the activity granularity of service,considering the reliability factors of the combination conditions between services,an improved model based on the combined service structure is proposed to compute the reliability of the activity based service composition.This model improves the accuracy on the basis of the original model,making the model more consistent with the application of an actual Web service system.Examples are used to verify the applicability of the improved reliability model and the effectiveness of the reliability analysis method.By analyzing the precision performance of the model and the sensitivity of the combined conditional reliability,the influence of the combination conditional reliability on the reliability of the entire Web service composition is studied,and the universality of the model is verified.3.For the problem that the complexity of complex service portfolio is difficult to assess,this paper presents an equivalent simplified reliability analysis method based on service composition flow at the service granularity level,and verifies the applicability and effectiveness of fault-tolerant technology for this analysis method.For the BPEL structured description of the service composition process,the reliability evaluation method for simplifying the combined service is studied.Based on the different granularity of structure-oriented research objects and the basic structure of business processes,based on the level of granularity of component services,simplified the simplification work on the structural relationship of BPEL,and the reliability analysis method of service composition and the overall reliability of combination of Web services are studied.In order to improve the overall reliability of Web services composition,this paper adopts software fault-tolerance technology and proposes a method for calculating the reliability of Web services composition based on fault-tolerant technology of recovery blocks.This thesis verifies the applicability and effectiveness of software fault-tolerant technology for improving the reliability of Web service composition through examples,and verifies the versatility of the proposed reliability analysis method for Web service composition system.