A Framework for the Management of Dynamic SLAs in Composite Service Scenarios

The advent of information and communication technology has changed the nature of business-to-business interaction among organizations. The use of electronic contracts with automated support for their management allows an increase of effectiveness and efficiency in contract processing, opening new possibilities for interaction among parties. Service Providers and their customers negotiate utility based Service Level Agreements (SLA) to determine costs and penalties based on the achieved performance levels. The global QoS to be provided to the end customer can be strongly affected by any violation on each single SLA. In order to prevent such violations, SLAs need to be flexible and dynamically adaptable. In this work we focus on the WS-Agreement specification, a Web Service protocol to establish agreements on the QoS level to be guaranteed in the provision of a service. We propose to enhance the flexibility of its approach by integrating new functionality to the protocol that enable the parties of a WS-Agreement to re-negotiate and modify its terms during the service provision.