SLO Auditing Task Analysis, Decomposition, and Specification

Service Level Objectives (SLOs) - the core of a Service Level Agreement (SLA) - reflect major Quality-of-Service (QoS) requirements of customers on a service for a given price. SLOs need to be updated, if those requirements change. This leads to an update of the SLO auditing implementation. However, in many existing implementations, efforts are required to adapt to SLO changes, and even more efforts are needed for dynamic adaptations. Thus, a new SLO auditing design is essential to be able to reduce such efforts to the bare minimum. This is especially essential, if the service landscape and relevant QoS parameters are changing frequently. Thus, to meet this core functional requirement of an automated auditing, a generic auditing framework, applicable to any SLO, is presented in this paper, where the analysis of a general audit task, the identification of its sequence of subtasks (functional decomposition), and the development of a respective audit specification for each subtask has been performed. A use case and examples are presented to describe and apply the concept in detail. An SLO auditing application, which was prototyped, is not restricted to a certain set of QoS parameters, but it is dynamically reconfigurable and extensible according to changing demands. The work shows that it has become quite easy to instantiate an auditing application for new SLOs. Additionally, third parties would be able to offer SLO auditing services to a service provider separately.