摘要

In this paper, we analyze the problems of existing Service Computing model and propose a model for managing and discovering services based on dynamic quality of services. This model consists of a Quality Measurement Center (QMC), which receives and analyzes the feedbacks of dynamic qualities of services to evaluate and rank the services according their dynamic qualities, and enables service consumer to search and discover services by the functional and/or QoS requirements;a QoS Spy, which feedbacks the real-time dynamic qualities of services to QMC and processes the fault detection and substitution of services;a Service Quality Calculator, which calculates the qualities of composite services based on their atomic services. With this model, we can evaluate and discover services on the Internet based on both functional and qualitative constraints. Meanwhile, this model is compatible with the basic principles of Service Computing, which are loosely coupled, protocol independent and location transparent. This model is the foundation of dynamic service discovery and substitution, and can improve the availability, scalability, and modifiability of service-based applications.

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