We have a DREAM: Distributed reactive programming with consistency guarantees

The reactive programming paradigm has been proposed to simplify the development of reactive systems. It relies on programming primitives to express dependencies between data items and on runtime/middleware support for automated propagation of changes. Despite this paradigm is receiving increasing attention, defining the precise semantics and the consistency guarantees for reactive programming in distributed environments is an open research problem. This paper targets such problem by studying the consistency guarantees for the propagation of changes in a distributed reactive system. In particular, it introduces three propagation semantics, namely causal, glitch free, and atomic, providing different trade-offs between costs and guarantees. Furthermore, it describes how these semantics are concretely implemented in a Distributed REActice Middleware (DREAM), which exploits a distributed event-based dispatching system to propagate changes. We compare the performance of DREAM in a wide range of scenarios. This allows us to study the overhead introduced by the different semantics in terms of network traffic and propagation delay and to assess the efficiency of DREAM in supporting distributed reactive systems. © 2014 ACM.