BNQM: مدل QoS بر اساس شبکه های بیزی برای ترکیب سرویس شبکه ای

The QoS attributes of Grid services play important roles in several tasks in Grid computing such as QoS-aware service composition, service negotiation, resource management, service discovery and scheduling. By considering the dynamic aspects of the Grid environments and also the uncertainty related to Grid services, in this paper, we present BNQM, a Bayesian network based probabilistic QoS Model for Grid service composition. Application of Bayesian network in QoS management makes it possible to indicate the conditional independence relationships among QoS attributes and to provide an effective probabilistic approach to predict new values for some QoS attributes while others are changed. Furthermore, we propose a framework for QoS-aware Grid service composition algorithms to use BNQM. This framework enables the QoS-aware Grid service composition algorithms to use up-to-date QoS values in the composition process. Several experiments conducted using the proposed framework and the achieved results indicate that BNQM is efficient in predicting the QoS values. Also, experiments reveal that using BNQM allows the QoS-aware Grid service composition approaches to use more precise and accurate QoS values, resulting in more precise composite Grid services from the QoS points of view.