A probabilistic approach to modeling and estimating the QoS of web-services-based workflows |
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Authors: | San-Yih Hwang Haojun Wang Jaideep Srivastava |
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Affiliation: | a Department of Information Management, National Sun Yat-sen University, Kaohsiung 80424, Taiwan b Department of Computer Science and Engineering, University of Minnesota, Minneapolis, MN 55455, USA c Department of Computer Science, Memorial University of Newfoundland, St. John’s, Newfoundland, Canada A1B 3X5 |
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Abstract: | Web services promise to become a key enabling technology for B2B e-commerce. One of the most-touted features of Web services is their capability to recursively construct a Web service as a workflow of other existing Web services. The quality of service (QoS) of Web-services-based workflows may be an essential determinant when selecting constituent Web services and determining the service-level agreement with users. To make such a selection possible, it is essential to estimate the QoS of a WS workflow based on the QoSs of its constituent WSs. In the context of WS workflow, this estimation can be made by a method called QoS aggregation. While most of the existing work on QoS aggregation treats the QoS as a deterministic value, we argue that due to some uncertainty related to a WS, it is more realistic to model its QoS as a random variable, and estimate the QoS of a WS workflow probabilistically. In this paper, we identify a set of QoS metrics in the context of WS workflows, and propose a unified probabilistic model for describing QoS values of a broader spectrum of atomic and composite Web services. Emulation data are used to demonstrate the efficiency and accuracy of the proposed approach. |
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Keywords: | Web service QoS Workflow QoS Web service composition Structural workflow Web services QoS aggregation |
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