The value of modeling and simulating business processes has recently received increased attention with the interest in business process re-engineering (BPR). Many re-engineering projects are done in conjunction with major system implementation projects, which can also benefit from modeling and simulation. As these system implementation projects become operational, the simulation models used to design and analyze them, and their associated business processes, have typically become obsolete or seen limited use. Significant additional value can be realized if these same models can become part of the operational systems being implemented, either as executive business monitoring tools or as business workflow control tools. This paper describes the characteristics of these real-time operational systems and the requirements for modeling and simulation tools that support transitioning to these types of systems. A purchase order request application is then presented as a concrete example of a ...