AutoSLAM (Automated SLA Management) is a policy-based framework for the automated establishment of Service Level Agreements (SLAs) in open, diverse and dynamic Service Oriented Architecture (SOA) environments. The novelty of our framework lies in the support for multiple SLA interaction models, giving service consumers and providers the flexibility to choose the one that is most appropriate in a given context, while simultaneously participating in multiple concurrent SLA interactions using different interaction models. As part of the framework, we present an overview of the reference architecture for the AutoSLAM middleware. We also present WS-SLAM, a domain-independent policy representation language that we have developed by extending the WS-Policy specification language. We validate our framework through a proof-of-concept prototype implementation for purchasing computing resources on Amazon EC2 under different contexts.