I. Introduction
Discrete event modeling can be considered a process of abstract knowledge representation of a real-world system. As a model, the representation should be executable within a simulation environment to analyze the modeled system with respect to modeling objectives. The model can vary according to the modelers' different viewpoints, such as event-oriented, process-oriented, object-oriented, etc. Among them, the object-oriented (OO) approach may be most compatible with a real-world system from the system-theoretic viewpoint of model representation [1]. The DEVS formalism [2], which represents a discrete event system from the system-theoretic viewpoint, is known to be compatible with the OO world view.