Service management has been a hot topic in the research community for a few years now, and a lot of research has been carried out. Due to the complexity of service management, most of the approaches pick out one particular problem only; most approaches focus on a specific scenario and try to develop a suitable solution: For example, [#!lmps99!#] deals with the integration of network and service management, but is restricted to switched ATM services. [#!hkp98!#] introduces a QoS MIB along with some necessary management functionality, but restricts itself to multimedia services. The management of Local Number Portability is covered in [#!akck99!#], but only applicable in Intelligent Networks (IN). [#!lewi00!#] reviews various approaches to develop service management systems; however, the focus is on software engineering, rather than on conceptual aspects of service management.
Since all these approaches focus on one particular problem of service management, they do not provide a generic service model that can be used in different scenarios and environments. Even the approaches that try to build a general service model do not meet our requirements: For example, [#!mnms00!#] develops a Service Management Architecture, which is limited to the phase of service usage; it does not consider the complete life cycle, one of our primary requirements. Furthermore, it does not address the problems arising from service hierarchies. Although [#!chko00!#] presents a very detailed model for service management, it does not consider service hierarchies, the relationships between customer and provider and the interactions that take place between these roles. According to [#!lew99!#], a service is composed of components. This definition does not meet our requirements, since it lacks a recursive definition of services composed of other (sub-) services and the associated management issues. Finally, [#!bsc99!#] presents an architecture that uses contracts based on service level agreements (SLAs) to share selective management information across administrative boundaries. However, this paper focuses on the definition of a language to formalize SLAs and does not cover the full service life cycle.