Distributed reactive simulation.

As systems become more complex, there is an increasing call for modeling capabilities to support tradespace decisions in a complex or system of systems environment. In simulation federations using Distributed Interactive Simulation (DIS) or High Level Architecture (HLA), simulations are federated sharing a subset of state data and event data with each other. They each have their own instances of initialization data, state data, events, time advance, and output data. The greatest challenge is to manage and coordinate these individual copies to form a coherent scenario run. This coordination and management task is intractable for any realistically complex scenario. It typically requires significant effort from a team of simulation professionals. This paper describes some early research for a proposed distributed reactive simulation paradigm that federates discrete functions while centrally maintaining the initialization data, state data, the event schedule, and time advance. In order to compose models, the analyst must first break them apart -- assembling a set of functions required by the systems of interest. We hypothesize that this approach will better enable analysis in the federated environment. Analysts will have greater access to initialization data and static properties. They will only have to look in one place for state trajectories and output data. They will be able to develop and compose functions that map to the systems architecture. The distributed reactive approach enables transparent verification and validation of the federation and supports design and execution of experiments.