Aggregation patterns of service level agreements

IT-based Service Markets require an enabling infrastructure to support Service Value Chains and service choreographies resulting from service composition scenarios. This will result into novel business models where services compose together hierarchically in a producer-consumer manner to form service chains of added value. Service Level Agreements (SLAs) are defined at various levels in such a hierarchy to ensure the expected quality of service for different stakeholders. Automation of service composition directly implies the aggregation of their corresponding SLAs. Aggregation of hierarchical SLAs leads to cross-enterprize business networks such as Virtual Enterprize Organizations (VEO), Extended Enterprizes and Value Networks. During the hierarchical aggregation of SLAs, certain SLA information pertaining to different stakeholders is meant to be restricted and can be only partially revealed to a subset of their business partners. Based on our notions of SLA Choreography and SLA-Views, we formally define an aggregation model to enable the automation of hierarchical aggregation of Service Level Agreements. The aggregation model leads to the discovery of various aggregation patterns in context with service composition and business collaboration.