Research On Several Key Technologies Of Web Service

Due to the rapid development of Internet technology and the rise of e-commerce, greatdemands for large numbers of new resources and applications emerge. Traditional softwaredevelopment architectures and methods could not satisfy the needs in complex enterpriseapplications. In order to handle the differences between platforms and protocols in the Webenvironment encountered in enterprise application integration and the collaboration in looselycoupled approaches, and to improve the efficiency of software development and integration,in addition to the sharing of information resources, a new software development architectureis proposed as a service-oriented architecture, namely SOA.SOA is an open, standard protocol that serves as a basic functional unit, a looselycoupled model framework, and also a design method. It can be applied to the existed isolatedsoftware applications into self-contained services. Applications may access these servicesthrough simple interfaces and communication protocols, which reduces the costs ofinteroperability, and supports the rapid development of enterprise applications. It can be usedswift development of enterprise applications, and may respond in time to the actual needs ofthe rapidly changing Internet environment. The research of SOA has received widespreadattention in recent years, from industry and academia.With the gradual popularization and application of SOA, Web service has been playingan increasingly significant role as a way to achieve SOA, also as a new type of distributedcomputing resources.Web services collect application logic, network technology and a variety of servicefunctional modules so that any company or individual could access them in any place andtime. With the extensive application of Web services, a series of major issues emerge on thelist. For example, in the instantiation of an abstract service process, how to select from a largenumber of candidate emerged Web services with the same quality of service for differentfunctions; in the dynamic Internet environment, how to ensure the reliability of the serviceportfolio under the possibility of a service failure or new services available, and so on.On the basis of Systematic analysis of related methods and the current research status athome and abroad, this dissertation is focused mainly on web services selection, servicesdeployment and fault-tolerance and recovery in runtime. The main achievements and content of this dissertation are summarized as following:(1) This thesis reviews the process of software development architectures and methods inthe past years, especially introduces the emerging SOA architecture. The analysis andsummary of research status of hot issues in the field of Web services is also given. All theseintroduce and summaries provide a solid foundation for the research of this thesis.(2)In order to solve the service selection problem, a discrete artificial bee colonyalgorithm called GABC was proposed and the corresponding optimization model wasestablished. According the character of the service selection problem, the genetic operator iscombined to form the foraging strategy of employed bees, and a greedy exploited strategy isdesigned for the onlookers. The attractive probability of a food source is redefined combiningits constraint violations. Through experiments, the algorithm was tested and compared withrelated algorithms. The results showed that GABC algorithm can effectively solve thisproblem.(3)A web services selection method based on collaborative filtering recommendation isproposed. In this dissertation, collaborative filtering recommendation method is indroduced toweb services selection field.According to the selection of similar web service users andcurrent user’s individual preferences, the unknown Qos values can be predicted, and then theweb services with top Qos values are Personalized recommendated to the current user.(4)For SLA-aware service composition problem, a multi-objective model for thisproblem is built and a multi-objective genetic optimization algorithm is also proposed in thispaper. According to the characteristics of this problem, genetic operations are redefined,including the introduction of individual domination strength into environmental selection, andthe redefinition of crossover strategy and individual mutation strategy incorporated with localsearch. At last, we analyzed our algorithm SMOGA, and compared it with recently proposedalgorithm E3-MOGA and NSGA-II for this problem on different scale test cases; theexperiments results show that algorithm SMOGA can solve this problem more effectively.(5)On the basis of already existing runtime fault-tolerance and recovery methods, a QoSconstrained based on similar web service substitue and Dynamic Partial Reconfigurationstrategy is proposed, and then the corresponding algorithm is given. The core idea of thisstragety is taking the redundant constraints into account and decomposing the globalconstraints into every member of service composition, and then the result of decomposing canbe used as constraint conditions of similar web service substitue and Dynamic PartialReconfiguration. Further, a web service components library and corresponding maintenancealgorithm are proposed. The research work and achievement in this dissertation has some theoretic andapplication value to improve the reliability and efficiency of Web services and servicecomposition.