The Convergence of AOP and Active Databases: Towards Reactive Middleware

Reactive behavior is rapidly becoming a key feature of modern software systems in such diverse areas as ubiquitous computing, autonomic systems, and event-based supply chain management. In this paper we analyze the convergence of techniques from aspect oriented programming, active databases and asynchronous notification systems to form reactive middleware. We identify the common core of abstractions and explain both commonalities and differences to start a dialogue across community boundaries. We present existing options for implementation of reactive software and analyze their run-time semantics. We do not advocate a particular approach but concentrate on identifying how the various disciplines can benefit from each other. We believe that AOP can solve the impedance mismatch found in reactive systems that are implemented through inherently static languages, while AOP can benefit from the active database community's experience with event detection/composition and fault tolerance in large scale systems. The result could be a solid foundation for the realization of reactive middleware services.