On the Specification and Negotiation of Quality of Service for Collaborative Services

The adoption of Web service technologies in dynamic business applications such as on-demanding computing or highly reconfigurable virtual enterprises advocates for methods and tools for describing and managing non-functional aspects of services, e.g., the reliability, accessibility and accuracy of a service. These properties are referred as quality of service (QoS). Failing to accurately specify and communicate quality details can lead to wrong and inconsistent expectations held by the service provider and service consumer and result in serious disagreement. Popular Web service description development and management solutions, e.g. WS-Policy and Web Service Level Agreement, do not properly cater for the specification and negotiation of quality related requirements for collaborative services. In this paper we present a comprehensive mechanism for the specification of quality requirements. The proposed approach allows service providers and consumers to explicitly define and adjust both higher level and concrete measurement requirements for quality of a service in a formally verifiable manner. As a result, quality negotiations can be performed effectively for the establishment of service provision agreements.