STRUCTURED MODELS AND DYNAMIC SYSTEMS ANALYSIS: THE INTEGRATION OF THE IDEF0/IDEF3 MODELING METHODS AND DISCRETE EVENT SIMULATION Larry Whitman Brian Huff Automation & Robotics Research Institute The University of Texas at Arlington 7300 Jack Newell Boulevard South Fort Worth, Texas 76118, U.S.A. Adrien Presley Division of Business and Accountancy Truman State University 100 East Normal Kirksville, Missouri 63501, U.S.A. ABSTRACT The role of modeling and simulation is receiving much press of late. However, the lack of practice in employing a link between the two is alarming. A static model is used to understand an enterprise or a system, and simulation is used for dynamic analysis. Generally, most models are considered static, whereas simulation is really a dynamic model. Static models are useful in achieving understanding of the enterprise. Simulations are useful in analyzing the behavior of the enterprise. Most enterprises develop and even maintain multiple types of models for different purposes. If a single model can be used to drive other modeling purposes, then model maintenance and development could be reduced. This paper describes the procedure necessary to use a static representation as the primary input for an animated simulation. It presents the additional steps necessary to annotate a static model for input to a dynamic model. Two commercial suites, WorkFlow Modeler to ServiceModel and ProSim to WITNESS, are compared and contrasted based on the respective ease of conversion from the static model to the dynamic model. Any user who purchases these products can follow the steps described in this paper for either of these product suites to generate a simulation from a static model. Finally, some general observations of using an existing IDEF (0 or 3) model to create a working simulation are presented along with conclusions. 1 INTRODUCTION The commonly accepted definition is that a model is a representation of reality. Generally, details that are unnecessary are not included. The typical uses (Nathan and Wood 1991) (Snodgrass 1993) (Reimann and Sarkis 1996) of modeling are: • To analyze and design the enterprise and its processes prior to implementation • To help reduce complexity • To communicate a common understanding of the system • To gain stakeholder buy-in • To act as a documentation tool for ISO 9000, TQM, Concurrent Engineering, and other efforts. A primary thrust of this research is to determine the feasibility of using a single master static model of the enterprise for multiple purposes. Previous research has presented a single suite perspective (Lingineni, Caraway et al. 1996) and uses custom developed software (Harrell and Field 1996). This research uses commercial products exclusively. For the static model, the research uses two specific methods for static representation, IDEF0 and IDEF3. Two concerns were: (1) the amount of required change of the IDEF methodology, and (2) the amount of additional annotation to the IDEF model required by the IDEF tool. Further explanation of these concerns follows. IDEF is a rigorous methodology. The reason for the rigor is to ensure a robust and complete representation. As part of this rigor, a thorough review process is used. The review cycle is enhanced by the rigid IDEF syntax. The syntax for IDEF is very explicit. A concern in utilizing an IDEF model to create a simulation is that the IDEF method would have to be compromised to enable the creation of a simulation directly from the IDEF model. However, it should also be noted that there are certain characteristics of IDEF modeling that have become considered standard practice, yet they are not a strict IDEF syntactic rule. This research found that the only changes to the methodology required were in these time-honored traditions, whereas no actual IDEF rule of syntax was broken. Proceedings of the 1997 Winter Simulation Conference ed. S. Andradóttir, K. J. Healy, D. H. Withers, and B. L. Nelson 518