云计算背景下面向服务组合的SLA动态管理机制研究

RESEARCH ON SERVICE COMPOSITION-ORIENTED DYNAMIC SLA MANAGEMENT MECHANISM IN CLOUD COMPUTING

组合服务通过组合和调用互联网环境中已有的Web服务实现更加复杂的业务功能。由于面向服务体系结构的分布式和松散耦合特征,稳定的QoS对于服务双方之间稳定的业务关系具有重要的作用,而服务等级协定SLA(Service Level Agreement)为云计算背景下的QoS管理提供了基础。针对服务组合场景下基于SLA的QoS管理问题,提出一个动态SLA管理框架,其中充分考虑到云计算环境下动态变化的客户数量和类型对于服务组合前端服务质量的不同需求。提出并实现了两种管理模式:定制模式与分级模式,并着重解决了管理过程中的后端SLA冲突问题。通过对服务组合绑定结构的动态规划和优选实现了组合服务前后端SLA的协调。根据所提出的管理框架实现了一个原型系统,验证了所提出框架和管理模式的有效性。

Composite services achieve a more complicated business functions through the composition and invocation of existing web services in internet environment. Due to the distribution and loosely couple characteristics of service-oriented architecture, stable QoS plays an important role in stable business relationship between the two sides of services. Service level agreement （SLA） provides the basis for QoS management for cloud computing context. According to SLA-based QoS management issues in service combinations scene, we propose a dynamic SLA management framework, which fully takes into account the different needs the customers numbers and types dynamically changing in cloud computing environment have on front-end of QoS in service composition. We also propose and implement two management modes： the custom mode and the hierarchical mode, and focus on solving the conflict of the back-end SLA in management process. We achieve the SLA coordination at both front and back ends of the composite services through dynamic planning and selection of composite services binding structure. We realise a prototype system based on the management framework proposed in this paper, and verify the effectiveness of the proposed framework and management modes.