Hindawi Publishing Corporation Journal of Applied Mathematics Volume 2013, Article ID 407267, 12 pages http://dx.doi.org/10.1155/2013/407267 Research Article A Fast Optimization Method for Reliability and Performance of Cloud Services Composition Application Zhao Wu, 1 Naixue Xiong, 2 Yannong Huang, 1 Qiong Gu, 1 Chunyang Hu, 1 Zhongbo Wu, 1 and Bo Hang 1 1 School of Mathematics and Computer Science, Hubei University of Arts and Science, Xiangyang 441053, China 2 School of Computer Science, Colorado Technical University, Colorado Springs, CO 80907, USA Correspondence should be addressed to Naixue Xiong; nxiong@coloradotech.edu Received 15 April 2013; Accepted 13 September 2013 Academic Editor: Rung Ching Chen Copyright © 2013 Zhao Wu et al. Tis 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. At present the cloud computing is one of the newest trends of distributed computation, which is propelling another important revolution of sofware industry. Te cloud services composition is one of the key techniques in sofware development. Te optimization for reliability and performance of cloud services composition application, which is a typical stochastic optimization problem, is confronted with severe challenges due to its randomness and long transaction, as well as the characteristics of the cloud computing resources such as openness and dynamic. Te traditional reliability and performance optimization techniques, for example, Markov model and state space analysis and so forth, have some defects such as being too time consuming and easy to cause state space explosion and unsatisfed the assumptions of component execution independence. To overcome these defects, we propose a fast optimization method for reliability and performance of cloud services composition application based on universal generating function and genetic algorithm in this paper. At frst, a reliability and performance model for cloud service composition application based on the multiple state system theory is presented. Ten the reliability and performance defnition based on universal generating function is proposed. Based on this, a fast reliability and performance optimization algorithm is presented. In the end, the illustrative examples are given. 1. Introduction Cloud computing is an emerging trend for the provision of IT infrastructure as services, with the potential of transforming the way of ofering business services [1]. Based on cloud computing platform, sofware development becomes promi- nent and accessible for all without the expensive investing in hardware resources and the managing and maintaining costs. On cloud computing platform, the cloud services com- position (CSC) is a fashionable approach of sofware devel- opment based on cloud services [2–4]. In the framework of CSC, cloud services are considered as self-contained, self-describing, modular applications that can be published, located, and invoked across the web. How to select and integrate cloud services to satisfy user’s functional requirements is an important issue, which has widely attracted attention of researchers [5]. Great progress has been made in this feld [6–8]. However, little research focused on reliability model and simulation for CSC. Recently, there has been growing interest in this feld. Meth- ods and technologies related to reliability model and simula- tion for CSC have attracted attention because they can fore- cast the QoS that users will obtain from CSC [9–11]. In addi- tion, it is helpful to analyze whether there are some relia- bility bottlenecks within CSC applications. Tus, reliability prediction is the basis of reliability optimization for the CSC applications. Te service-oriented architecture (SOA) is the most rep- resentative technological architecture to build the cloud ser- vices application on cloud computing platform [12–14]. How- ever, because SOA supposed by services composition tech- nique is of dynamic and cooperative essential characteristic, the traditional sofware reliability prediction methods are not suitable to the cloud services application based on SOA. From the aspect of sofware architecture, cloud services application is a kind of Internetware based on cloud services,