Implementation of the DEVS Formalism over the HLA/RTI: Problems and Solutions

This paper describes the design and development of DEVS/HLA, an HLA-compliant modeling and simulation environment that supports high level model building using the DEVS (Discrete Event System Specification) methodology, a sound formal M&S framework. After a brief review of the DEVS formalism, we discuss the implementation of the formalism in C++ as a layer above the Runtime Infrastructure (RTI) released by the Defense Modeling Simulation Organization (DMSO) to implement the HLA standard. This leads to a consideration of alternatives for implementing the DEVS protocol which allow for efficient event-based simulation, maximally exploit HLA primitives, and support the full range of DEVS expressive power, which has been shown to subsume all discrete event system behaviors. Direct mapping of the DEVS protocol incurs a mismatch with the HLA specification. We present an alternative solution involving off-loading some of the time-management on a coordinator federate. 1 This work was supported by Advance Simulation Technology Thrust (ASTT) DARPA Contract N6133997K-0007