QoS-Based Service Ranking and Selection for Service-Based Systems

To facilitate rapid development of service-based systems (SBS), many service discovering and matching techniques have been developed to find services according to users´ functionality requirements. However, users usually also have requirements on non-functional qualities of services (QoS), such as throughput, delay, reliability and security, which are also critical for the success of SBS. In this paper, a QoS-based service ranking and selection approach is presented to help users to select the service that best satisfies users´ QoS requirements from a set of services having already satisfied users´ functionality requirements. To determine how well a service satisfies users´ concerned QoS requirements, a set of functions is presented to normalize services´ QoS on various QoS aspects with different metrics and scales, compute services´ satisfaction scores on each QoS aspect, and combine each services´ satisfaction scores on all QoS aspects together as an overall satisfaction scores. Compared with existing service ranking and selection techniques, our approach has the following advantages: 1) selects the service that best satisfies users QoS requirements instead of the service with the best QoS which may be much overqualified for the users´ QoS requirements, 2) improves the flexibility in users´ QoS requirement specification, and 3) uses the prospect theory to more accurately model the relation between services´ QoS and their satisfaction scores.