ML-SLA: Multi-Level Service Level Agreements for Highly Flexible IoT Services

Service systems in upcoming application domains like the Internet of Things (IoT) have a high demand for dynamic changes of provided service quality and related pricing. Changes can be requested by service consumers to address adjusted requirements at application level or by service providers to accommodate resource constraints. Anyway, traditional approaches to handle Service Level Agreements (SLA) are limited to a predefined service quality provided for a fixed price. Changed application requirements or SLA violations result in a re-negotiation, usually combined with a service termination. In this paper we present a novel approach called Multi-Level SLA (ML-SLA) that supports the negotiation of multiple service levels combined with an extended service runtime environment. It supports dynamic level switches during the execution phase of an SLA initiated by service consumers or providers. An evaluation based on the implementation of the Multi-Level SLA concept demonstrates that quality levels of services can be efficiently changed without service termination.