This is a Java reference implementation of dynamic event-driven actors runtime aiming at providing adequate abstraction levels and mechanisms for modelling and developing (distributed) event-based systems. DERA leverages the intrinsic loose coupling of event-driven communication styles to support various kinds of run-time evolution and adaptation (i.e., enabling run-time flexibility) while minimizing the non-deterministic nature of traditional event-based applications (i.e., supporting formal analysis).