DEVS-DOC: a modeling and simulation environment enabling distributed codesign

An approach to modeling and simulating distributed object computing systems as a set of software components mapped onto a set of networked processing nodes is presented. The modeling approach has clearly separated hardware and software components enabling systems level, distributed codesign engineering. The distributed codesign engineering refers to a system-theoretic approach to concurrent hardware and software systems engineering that provides a tractable method for analyzing the inherent complexities that arise in distributed computing systems. A software abstraction forms a distributed cooperative object (DCO) model to represent interacting software objects. A hardware abstraction forms a loosely coupled network (LCN) model of processing nodes, network gates and interconnecting communication links. The distribution of DCO software across LCN processors forms an object system mapping (OSM). This OSM provides a sufficient specification to allow simulation investigations. In simulation, the behavioral dynamics of the interacting DCO software components load and compete for LCN processing and networking resources. The LCN resource constraints thus impose performance constraints on the interactions of the DCO software objects. Class models of the DCO, LCN, and OSM component structures and behavior dynamics were formally characterized using the discrete event system specification (DEVs) formalism. These class model specifications were implemented in DEVSJAVA, a Java implementation of DEVS. Class models of experimental frame components were developed and implemented to facilitate analysis of the interdependent distributed system behaviors during simulations. Our DEVS-DOC M&S environment enables distributed systems architects, integration engineers and system designers to analyze performance and examine engineering trades of system structures, topologies and technologies. A case study demonstrates the ability to model and simulate a real world system and the complex interactions that arise in distributed computing systems