中文摘要：

已有网格服务可靠性与性能模型均假设资源节点和链路可靠性服从独立指数分布，这种假设有利于简化建模和分析，但同时也限制了已有模型的应用范围，因为在实际网格环境中，资源节点和链路可靠性存在相关性，即寿命服从多元指教分布．针对这个问题，在已有的树型网格服务模型的基础上，把资源节点和链路的寿命分布从一元指数分布拓展到多元指数分布，提出一种寿命服从多元指数分布的树型网格服务可靠性与性能模型，同时给出该模型的求解算法．寿命服从多元指数分布的树型网格服务可靠性与性能模型求解算法通过构造互斥分解树，把模型求解问题分解成互斥极小项来获得模型的解．实例和理论对比分析表明：寿命服从多元指数分布的树型网格服务可靠性与性能模型不仅兼容已有树型网格服务模型，而且能够适用于寿命服从多元指数分布的树型网格服务计算环境建模，同时寿命服从多元指数分布的树型网格服务可靠性与性能模型求解算法不仅能更有效求解已有树型网格服务模型，而且可以求解更复杂的多元指数分布树型网格服务模型，与已有网格服务模型求解算法相比具有更强的通用性和更高的算法效率．

英文摘要：

The previous models for reliability and performance of grid services assume that all the states of resource nodes and links are s-independent. This assumption can simplify the modeling and analysis. However it limits the applicability of the models because all the states of resource nodes and links in fact are s-dependent and follow the multivariate exponential distribution. In order to address this issue, this paper presents a novel model for reliability and performance of tree-structured grid service based on multivariate exponential distribution, which assumes that all the states of resource nodes and links are s-dependent and follow the multivariate exponential distribution. Based on the model, a novel algorithm for evaluating the grid service performance distribution and the service reliability indices is suggested. This algorithm constructs a tree of disjoint products and gets the solution of model in the form of disjoint products. The illustrative example and experimental results show that the proposed model for reliability and performance of tree-structured grid service based on multivariate exponential distribution can not only be compatible with previous tree-structured grid service model but also be adapt to the complex grid services in which all the states of resource nodes and links are s-dependent and follow the multivariate exponential distribution; and that the novel algorithm based on tree of disjoint products outperforms the previous algorithms.