Trusted Mechanism And Algorithms Of Service Collaboration ForInternet Of Service

With the development of Web Services techonology, service systems with single function have been unable to be satified by the user with complex requirements. Therefore, Internet of Service which in order to satify user’s individual requirements via networking and integrating service systems have become the focus attention in the Web service research area. However, the open characteristic of Internet of Service and the rapid evolution of service resources cause the trustworthy problem when collaborating with unkown services. Currently, the trust problem in the scenario of service collaboration has become one of the key factors which hindered the development of Internet of Service.In order to solve the problem described above, we conducted a study on two aspects of service collaboration in Internet of Service based on the analysis of the challenges which might face with when doing such a research. One is how to select a trustworthy component service and the other is trust-aware service selection in composition. We considered the problem of services’crebility and the reliability of service systems in both when defining the trustworthy problem of service collaboration. Our main work and contributions include:(1) We proposed a trustworthy management framework for service collaboration. The process of service collaboration includes multiple setps such as service selection, service composition, resource optimazition, service evolution and process reconstruction. Therefore, consider the problem of trustworthy service collaboration must involve various aspects of service collaboration. We firstly proposed three basic mechanisms that support trustworthy service collaboration which include thorough trust evaluation mechanism, balanced trust-aware service selection in composition and reliable sevice fault tolerance and process reconstruction mechanism for Web services. Based on the three mechanisms, we proposed a trustworthy management framework for service collaboration which lay sound foundation for our work. (2) We proposed a social network based trust model. In a service-oriented environment, it is inevitable and indeed quite common to deal with web services, whose reliability is unknown to the users. The reputation system is a popular technique currently used for providing a global quality score of a service provider to requesters. However, such global information is far from sufficient for service requesters to choose the most qualified services. In order to tackle this problem, we present a trust based architecture containing a computational trust model for quantifying and comparing the trustworthiness of services. In this trust model, we firstly construct a network based on the direct trust relations between participants and rating similarity in service oriented environments, then propose an algorithm for propagating trust in the social network based environment which can produce personalized trust information for a specific service requester, and finally implement the trust model and simulate various malicious behaviors in not only dense but also sparse networks which can verify the attack-resistant and robustness of the proposed approach. The experiment results also demonstrate the feasibility and benefit of the approach.(3) Proposed an ontology based trust model for bipartite service network. Tthe special topology structure of bipartite service network causes the trust information unable to be propagated directly among service requesters. In addition, different service requesters have different preferences and satisfaction criterion to the same service which cause trust evaluation of services not only satisify the accuracy of the objective information but also should consider the requirements of entities. In order to solve the problem mentioned above, we proposed an ontology based trust model which consist three components. We first introduce an review ontology to structure express the feedback by the users, then construct the trust network between service requesters based on the review ontology, finally get the review information from the witnesses to evaluate the trustworthiness of a specific service. Experiments results also demonstrate the feasibility and benefit of the approach.(4) With the rapid increasing number of the independently developed web services that provide the same or similar functionalities but differ in quality ofservice (QoS), the service composition can be considered as a problem on the selection of component services in accordance with user’s QoS requirements, a practice known as QoS-aware service composition problem. However, current solutions are not only not suitable for most real-time decision-making service composition applications which are required to obtain an optimal result in reasonable time, but also not as reliable as intended because in an open service-oriented environment, services may be unreliable or even harmful. In this paper, we present a trust based approach which addresses the issue of Web service composition in a way that maximizes the QoS value of composite services expressed as utility functions over a set of QoS attributes, while satisfying the constraints set by the end-users and promising all the selected services are trustworthy. The proposed heuristic algorithm consists of three steps:first, a trust based local selection method is used to filter untrustworthy component services. Second, convex hulls are constructed for reducing the search space for each task. Finally, a heuristic global optimization approach based on M-HEU is used to obtain the near-optimal solution.The results of the experiments evaluation demonstrate that our approach can obtain a close-to-optimal and trustworthy solution in a reasonable time.