PROSA - Process-Oriented Service Level Agreements for Providing a Single Point of Contract

The fundamental paradigm shift from a productto a service-oriented economy implies novel technical and organizational challenges. The value generated by a service is mainly represented by intangible elements exposed at execution (Hill 1977). Therefore, a service consumer expects a service to function reliably and to deliver a consistent outcome at a variety of levels, i.e. Quality of Service (QoS). To provide, control and assure QoS it is necessary to focus on functional properties of a service as well as on non-functional aspects. The context of a service also influences its quality, which is experienced by the consumer, e.g. the partner network that comes with a service, its reputation in certain communities or advertisement campaigns promoting the service. From an economic perspective, QoS is the most important characteristic that differentiates service offerings and leverages market advantage, as price competition is tough due to low variable costs of service provisioning. Thus, QoS is the key criterion to keep the business side competitive as it has serious implications on the provider and consumer side (Papazoglou 2008). The provision of services with a defined QoS over electronic networks such as the Web is challenging due to issues like infrastructure problems, unpredictable reliability, low performance of Web protocols and many more. In addition, the distributed nature of Web service environments and their high degree of complexity requires a comprehensive description of Web service quality characteristics, both functional and non-functional. For detailed information about the main aspects of