【作者】 付毅；

【导师】 胡志刚；

【作者基本信息】 中南大学 ， 计算机应用技术， 2009， 硕士

【摘要】 随着网格计算逐步从科研领域走向更为广泛的商业应用,以及对用户服务质量需求的日益重视,信任和声誉等基于社群的自适应度量机制为有效支撑广域范围的资源共享和协作提供了重要保障。本文针对服务网格环境,研究一种集可扩展性、动态自适应性和健壮性为一体的信任评估机制,以期提高服务质量。基于对服务网格体系结构的研究与分析,论文首先提出了一个可扩展的网格服务QoS管理框架,提出从应用领域的角度定制网格服务QoS模型,介绍了QoS信息采集和QoS属性度量方法。针对当前QoS可信度评估没有考虑服务分级以及应用QoS约束的特点,研究并提出了一个基于贝叶斯网络的QoS可信度评估方法。该方法根据服务QoS历史记录建立贝叶斯网络,依据用户提出的不同QoS需求来评估服务QoS可信度。实验表明该方法在服务性能动态变化的情况下具有较强的适应性。针对网格信任评估现状,提出了一个可扩展的服务网格信任模型QoSTrust。定义了QoS满意度和服务评分可信度的概念,通过描述服务QoS属性满足SLA协定的程度和用户评分的可信程度,减少用户评分的主观性。在信任演化方面,为更好地满足用户QoS需求,评估直接信任时考虑了QoS约束;为了提高信任值计算的效率,引入VO层的信任关系以减少声誉迭代算法的开销。实验结果表明QoSTrust能合理评估信任值,实现可信服务选择,有效支撑服务质量需求。更多还原

【Abstract】 With the developing of Grid computing, Grid has extended its territory from traditional computing Grid to service-oriented Grid, aiming to realize e-Science and e-Business at the global level. Users pay more and more attention to QoS demand. Community-based adaptive metrics such as trust and reputation serve as building blocks to support QoS requirements. There is an urgent need for a new trust mechanism for service-oriented Gird with scalability, dynamic adaptability and robustness in a whole.First, an extensible QoS information management framework based on service-oriented Grid architecture is proposed in this thesis. It emphasizes that QoS model is customizable and the technologies on collecting, storing, measuring QoS information are introduced.Current research on QoS trustworthiness evaluation lacks of considering application’s QoS constraints and differentiated service. To ensure this, a Bayesian Network based approach is presented to evaluate the trustworthiness of Grid service. The approach employs performance history to construct an evaluation model, which ranks the services in terms of their trustworthiness of QoS information and considers degree of consistency in QoS provision. Simulative results show that the proposed approach can effectively enhance trustworthiness of service information and improve reliability of service selection.A scalable trust model named QoSTrust is proposed based on current trust and reputation research in Grid and P2P network. In order to reduce the subjectivity of user’s rating, two new concepts, namely Satisfactoriness of QoS and Trustworthiness of Service Rating, are defined in the proposed model, which are used to evaluate delivered QoS that fulfills agreed QoS in SLA quantitatively and trustworthiness of users’ rating respectively. In trust inference, direct trust is defined with QoS constraints to meet user’s QoS requirements better and VO level’ trust relations are introduced to reduce the overhead of the reputation iterative algorithm. Simulative results show that the establishment of trust is more efficient. Also, when using the proposed model for service selection, it outperforms other models in terms of query success rate and user’s satisfaction.更多还原