Quality of Service (QoS) Contract Specification, Establishment, and Monitoring for Service Level Management

This paper describes an approach and the architecture of Quality of Service (QoS) contract specification, establishment, and monitoring for Service Level Management (SLM). Contract is an essential concept in SLM. The service consumer side and the service provider side must share common understanding of QoS characteristics and agree on the common language for specifying desired QoS parameters in the form of QoS contracts. A service consumer must also negotiate with a service provider to establish mutually agreed QoS contracts for an interactive session. The service provider must consider QoS contracts already agreed upon with existing consumers and system resource conditions in establishing a new QoS contract. Similarly, a service consumer must be prepared in revising its contract with the service provider as conditions change over time. Once a QoS contract is established, SLM must provide monitoring to make sure that the service is provided at agreed QoS parameter range. If necessary, SLM must activate adaptation mechanisms to bring the service quality to the desired level. A case study is presented to validate the QoS contract management design approach and architecture for SLM.