| Today web services have been widely applied to fields such as e-commerce. However, web services usually provide single function and there are numerous services with different quality of services and similar functions. In order to better facilitate consumers’ discovery and selection of services, some service providers even counterfeit and cheat. Hence, it’s urgent to handle how to design an efficient service composition modeling framework, compositing web services spreading on the Internet to increase efficiency of reuse.This thesis first analyzes related research on service selection and service composition modeling framework, and models quality of service(QoS). A trustworthy model based on dynamic Bayesian network is proposed, which consists of direct trust, recommendation trust, consistency trust of QoS monitoring and computing method of synthesized trust.According to data stream and control stream, this thesis analyzes the relationship among services and formally describes it. An algorithm supporting dynamic service composition is proposed to intergrate constraint methods of QoS and service behavior. The algorithm first analyzes the candidate service set, and excludes services with lower trust by multi-threading approach. With behavior restriction among services, continue excluding service composition schemes is conducted. Based on the structure of service composition, synthesized trust can be computed, which facilitates fast dynamic service selection.A prototype system of trustworthy service composition modeling is developed. According to the characteristics of OWL_S, the system expands OWL_S to make describing non-functional property of services possible. Combining process specification language(PSL) with visual process modeling language(VPML), a composition service modeling language(CSML) is designed based on VPML for supporting visual modeling of service composition. A case study is provided to demonstrate the feasibility of the proposed prototype system. |
PDF Full Text Request