A reference architecture for multi-level SLA management

There is a global trend towards service-orientation, both for organizing business interactions but also in modern IT architectures. At the business-level, service industries are becoming the dominating sector in which solutions are flexibly composed out of networked services. At the IT level, the paradigms of Service-Oriented Architecture and Cloud Computing realize service-orientation for both software and infrastructure services. Again, flexible composition across different layers is a major advantage of this paradigm. Service Level Agreements (SLA) are a common approach for specifying the exact conditions under which services are to be delivered and, thus, are a prerequisite for supporting the flexible trading of services. However, typical SLAs are just specified at a single layer and do not allow service providers to manage their service stack accordingly. They have no insight on how SLAs at one layer translate to metrics or parameters at the various lower layers of the service stack. In this paper, we present a reference architecture for a multi-level SLA management framework. We discuss the fundamental concepts and detail the main architectural components and interfaces. Furthermore, we show how the framework can be flexibly used for different industrial scenarios