Policy enforcement within emerging distributed, event-based systems

Computing is becoming increasingly ubiquitous. To fully realise the potential of emerging distributed systems, it must be possible to manage and bring together (coordinate) system components in various ways---perhaps for purposes and in circumstances not contemplated by their designers. Therefore, we believe that the application logic embodied in components should be separated from the policy that specifies where, how and for what purpose they should be used. This paper explores how supporting infrastructure can enable policy, representing high-level (user) or systems concerns, to drive system functionality. SBUS is a middleware that supports secure, dynamic reconfiguration, providing the means for policy enforcement across system components. We present SBUS to demonstrate the practical aspects and design considerations in a) making infrastructure policy-compliant, and b) leveraging the dynamic policy enforcement capabilities to achieve particular functional goals.