Research And Implementation Of A QoS - Driven Adaptive Service Composition Model

Service composition system based on service oriented architecture is a distributed computing application,which is composed by Web Services published on the Internet.Its main purpose is to composite heterogeneous Web services to address user complicated needs according to business work flow.Because the network environment,the user needs,and Web Services dynamic change,it is important that how to generate a real-time and dynamic service composition application with changes of user needs and environment to avoid the static service composition application which lacks of self-adaptive ability affecting quality of application.This is a challenge existed in the research field of service composition.In order to solve this problem,many scholars have carried on the related subject in the research,argumentation and analysis, respectively,puts forward the local and global optimal self-adaptive service composition strategy.We adopt a combination of local and global optimum strategy.This solution can make the system adapt to environmental changes and produce a service composition sequence. The service composition sequence which dynamically is bound and executed can be nearest to the user request service level agreements.According to the requirements of service composition,firstly,this paper presents the QoS driven self-adaptive service composition model framework,including the system architecture and the function of the model.Secondly,design the QoS driven self-adaptive service composition mechanism,including SLA model and QoS of service composition model,and use QoS attribute value and SLA attribute value to solve objective function in order to obtain service composition sequence that is the most close to user needs.Meanwhile present the run-time self-adaptive execution process and self-adaptive algorithm of service composition.Thirdly,Model service composition and use Tableau algorithm to verify whether service composition system satisfies CTL constraints. Design and realize application prototype GKASCS supporting QoS driven self-adaptive service composition.Compared with service composition without self-adaptive mechanism,GKASCS can adapt to environment changes and guarantee consistency and reliability of service composition application.At last,aimed at the problems and the insufficiency,subsequent work are prospected.