严格服务等级约定的区分Web服务技术研究

随着Internet的普及和Web应用的发展，满足客户不同业务需求成为人们关注的问题．该文基于业务类的访问资源需求和服务等级给出了一种资源划分策略，用来确定业务类在访问率波动较小条件下达到服务级别所需的资源；提出一种资源效用控制机制，用来适应访问的突发性和保证业务类服务等级要求．通过按周期进行资源划分，同时利用资源控制机制来适应周期内的访问突发，得到了严格服务等级约定的区分Web服务(简称SLADS)．文章通过建立原型与其它方法进行了实验比较，结果表明SLADS方法能够有效支持业务类的严格服务等级和提高资源利用率．

Research on Differentiated Web Services with Strict Service-Level-Agreement

This paper proposes a policy, SLADS, to support differentiated web services with strict service level agreement (SLA) among the request classes. First it introduces a method to partition the resources for each class with its resource demand and SLA requirement which meet SLA requirements for the classes under small request fluctuation. Then a mechanism for resource utility control, which is based on request scheduling and admission control, is presented to adapt request burstiness in each period. SLADS can provide fair services for low priority classes when there are adequate resources, and maintain the SLA for the high priority classes by degrading services of the low priority classes firstly when the system is heavily loaded. A prototype based on SLADS is implemented in a cluster-based web server and we compare it with other proposed methods. The experiments show that the proposed technique supports differentiated services with strict SLA efficiently and increases the resource utility.