Reactive HLA-based Distributed Simulation Systems with RxHLA

Distributed and Real-Time Simulation represents a solid and effective approach to manage the ever-increasing complexity of modern systems. The IEEE 1516-2010 for Modeling and Simulation (M&S) High Level Architecture (HLA) is an interoperability standard for Distributed Simulation (DS) used to support analysis, engineering and training in different research and industrial domains. Using HLA, simulation entities (called Federates) can interact (that is, to publish and/or subscribe ObjectClasses and InteractionClasses, to communicate data, and to synchronize actions) with other Federates in a common simulation environment (called Federation) through the services provided by the Run-Time Infrastructure (RTI) that abstract and hide the details of the computing infrastructures making them communicable. In today's HLA-DS systems, in which simulation entities are highly concurrent, distributed, and the interactions among them are asynchronous, great benefits can derive from the exploitation of reactive approaches, tools and techniques so as to reactively manage the Federates' communication flow instead of handling it through HLA Callbacks. In this context, the paper presents a solution for defining reactive HLA Federates along with the RxHLA software framework that aims at defining and building reactive, concurrent, and distributed time/event-driven simulation components (Federates) in a r.eactive fashion.