Compatibility Analysis of WSLA Service Level Objectives

In On Demand Service environments, both a client and a service provider need to make sure of their common agreements on the quality of service (QoS), i.e., performance, reliability and availability, prior to accessing a managed service. This is due to the fact that varied and customized requests of individual clients may not always match the QoS supported by an autonomous service. To mitigate such a potential incompatibility, an automated analysis is necessary to make sure that specific QoS requirements by a client can be satisfied by the QoS supported by a service. In different scenarios, such an analysis can be performed either by the client, or the provider or both. Note that even if both the client and service use a common syntactic expression language, semantic differences in supported/requested metrics and service level expressions make this a very challenging problem. This paper presents an algorithm for automated compatibility analysis assuming QoS is expressed using a rich and flexible specification language such as the Web Service Level Agreement (WSLA).