Specification of Service Level Agreements: Problems, Principles and Practices

Software intensive systems (SIS) increasingly influence the ability of enterprises to be competitive in continuously changing market situations. The integration of these systems into organizations, and in particular the subsequent exploitation, maintenance and service activities, have become of utmost importance. Unfortunately the area of exploitation and operation, also known as service management, is still rather immature. Service management covers services such as performance and availability support, end-user and help desk support, education, and maintenance. One of the main concepts of service management is the Service Level Agreement (SLA). The goal of an SLA is to bridge the gap between service provider and users or customers. However, there exist many problems and unsolved questions regarding the specification and the quantification of SLAs. This paper addresses the specification of SLAs on the basis of three well-founded service management principles, respectively: 'continuity in service management,’ the pit/shell principle of a service, and the principle of specifying the quality of both a service process and a service object. Finally, the paper addresses the validation of these principles in practice.