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.