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Scientific Programming
Volume 14 (2006), Issue 3-4, Pages 251-265

A Stochastic Model for Workflow QoS Evaluation

Yunni Xia, H.P. Wang, Y. Huang, and L. Yuan

School of Electronic Engineering and Computer Science, Peking University, Beijing, China

Received 30 December 2006; Accepted 30 December 2006

Copyright © 2006 Hindawi Publishing Corporation. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Quality (QoS) prediction is one of the most important research topics of workflow. In this paper, we propose a stochastic model to evaluate QoS (make-span, reliability and cost) of workflow systems based on QWF-net, which extends traditional WF-net by associating tasks with firing-rate, failure-rate and cost-coefficient. Through a case study, we show that our framework is capable of modeling real-world workflow-based application. Also, Monte-carlo simulation in the case study indicates our analytical methods are consistent with simulation. We also present a sensitivity analysis technique to identify QoS bottleneck.The paper concludes with a comparison between our approach and related work.