Functional approach for the architecture design of a payroll system

In this paper we propose a functional model for the design and testing of the payroll system, a business application in the real world. With domain of the user actions and range of the system reactions, the function simulates the entire system, and defines the mathematical aspect of the application in high level of view. We present the detailed steps to formalize the model from system states and associated activities, to state transition function and transition diagram. Individual component is modelled by the stream processing functions which map the input options from the user to the output reactions of the condition states. Based on the transition function, a simulation program is developed for architecture design and user training.