Cloud Services Representation using SLA Composition

SLA-aware Cloud platforms need mechanisms to represent, store and retrieve Cloud services. Usually services changes between different platforms, custom models are built to capture this information and ad-hoc implementations used to store and retrieve it. This paper propose a generic methodology for the representation of Cloud services. This methodology uses the WS-Agreement specification for capturing and manipulation arbitrary services using SLA fragments. SLA fragments are composed on the fly in response to user request. A SLA composition algorithm enables a prototype implementation of the methodology in a SLA-aware Cloud platform. This methodology provides the genericity, extensibility and flexibility to unify the modeling of Cloud services. Finally a use case provides a quantitative measure of the utility provided by the methodology from a Cloud user and Cloud provider point of view.