中文摘要：

随着云计算的普及，saas作为一种新的软件交付模式得到了越来越广泛地关注．为了支持高速业务发展带来的大量用户的访问请求，多租约SaaS应用需要负载均衡机制以支持可扩展性．本文从对多租约saas应用用户需求的分析入手。提出了一种面向租约功能类型的服务器负载模型和面向租约用户非功能需求的执行请求按需分配算法，设计了一个面向多租约saas应用的负载均衡系统．实验表明本文提出的面向多租约SaaS应用的负载均衡机制能在满足不同租约用户需求的同时提高系统整体执行效率．

英文摘要：

With the rapid development of cloud computing, SaaS （ Software as a Service） has been popular as a new software delivery pattern in both industry and academia. Achieving load balancing is essential to ensure scalability in multi-tenant SaaS applications. This paper proposes a load balancing mechanism for multi-tenant SaaS application. Based on analysis of customized user requirements, this paper puts forward a tenant function type oriented load index model, non-functional requirements oriented requests dispatching algorithms and a load balancing system. The experimental results show that the proposed load balancing mechanism improves the overall execution effectiveness, and satisfies the needs of users with different QoS requirements as well.