A Formal Model of QoS-Aware Web Service Orchestration Engine

QoS-aware applications can satisfy not only the functional requirements of the customers, but also the QoS requirements. QoS-aware Web Service orchestration translates the QoS requirements of the customers into those of its component Web Services. In a system viewpoint, we discuss issues on QoS-aware Web Service orchestration and design a typical QoS-aware Web Service orchestration engine called QoS-WSOE. More importantly, we establish a formal model of QoS-WSOE based on actor systems theory. Within the formal model, we use a three-layered pyramidal structure to capture the requirements of the customers with a concept named QoS-Aware WSO Service, characteristics of QoS-WSOE with a concept named QoS-Aware WSO System, and structures and behaviors of QoS-WSOE with a concept named QoS-Aware WSO Behavior. Conclusions showing that a system with QoS-Aware WSO Behavior is a QoS-Aware WSO System and further can provide QoS-Aware WSO Service are drawn.