Discrete event system homomorphisms: Design and implementation of quantization-based distributed simulation environment

Abstract

The demand for parallel and distributed discrete event simulation (PDES) is rapidly growing due to the advent of middleware programs which allow multiple processes running on one or more machines to interact across networks. High Level Architecture (HLA) proposed by DoD is the standard middleware designed for distributed simulation environment. DEVS/HLA, developed in this dissertation, is a parallel and distributed modeling and simulation environment which employs a sound system theory, modeling formalism (extended DEVS) and system homomorphisms in its design. The environment includes a highly efficient message filtering scheme called quantization and is based on a risk-free PDES simulation protocol that exploits simultaneous events. In its implementation, DEVS/HLA employs hierarchical and modular object-oriented technology. To the user it presents a high level modeling paradigm and a highly reliable distributed HLA-compliant environment. This dissertation presents an analysis of quantization-based message filtering and some very promising empirical results that clarify the tradeoff between reduced message bandwidth demand and error incurred due to message reduction. The results relate bandwidth utilization and error against quantum size for federations executing on DEVS/HLA in Unix and NT networking platforms in both LAN and WAN environments. The theoretical and empirical results indicate that predictive quantization can be very scaleable due to reduced local computation demands as well as having extremely favorable communication reduction/simulation fidelity tradeoffs. How the solution extends to real-time DEVS simulation and implications for the design of real time infrastructures are topics for further research.