The Model Of Service Selection And Combination Based On QoS Under Pervasive Environment

With the development of information technology, the methods of computation have beentransiting from the host computing, desktop computing to pervasive computing. Pervasivecomputing environment is a dynamic environment, which the device in it has strongheterogeneity and instability. Compared with the common services in the Internetenvironment, the quality of service in the pervasive environment depends mainly on thestability of the environment and equipment. Different devices and dynamic network havedifferent quality of service, and there are a lot of services with similar functions in thenetwork. So in order to ensure service reliability, it is necessary to choose services based onthe quality of services. Selecting the trusted service according to the quality of the service cangreatly reduce the quality problems brought by untrusted service and security issues.Users sometimes demand functions that a single service can not satisfy, in order to savenetwork resources and improve the reusability of services, service composition is an effectiveway to solve this problem. For the above reasons, this paper proposes a QoS-based serviceselection and combination methods under pervasive environment. And due to theheterogeneity and instability of the device in the pervasive environment, this paper proposethe access control management framework to ensure the security in services accessing underthe pervasive environment.The proposed method is mainly composed of three parts. First, according to thecharacteristics of pervasive computing environments, analysising that context-aware canprovide users with composition of services which is relevant to networks, devices and usercontext information, this method is flexible to adapt to change. For these reasons, this papaerproposes the service composition process based on context-aware under pervasiveenvironment. The method can collecting context information, modeling and reasoning inpervasive computing environments, to get the services that meet user’s needs.Secondly, in order to ensure the quality of service, this paper extends the serviceselection step. There are many features similar services when discover services, however, thequality of services is not the same, in order to ensure quality of service, we propose the QoS-based service selection method. The method calculates the QoS parameters of theservices which meet the user’s needs, in order to get the value of service satisfaction.According to the results, form a list which ranks from the highest value to the lowest. Thenuser selects the appropriate services according to the list.Due to the characteristics of pervasive environment, we have to consider the securityproblem. To solve this problem, we propose a framework of Equipment safety certification.The framework verifies the service which needs to access device, the device can be verifiedby the security certificate, only the device with certificate can access the service. This methodcan protect the privacy of universal network service accessing, and reduce the loss brought byunauthorized service accessing the Ubiquitous.