Combining Static and Dynamic Modelling Methods: A Comparison of Four Methods

A conceptual model of a system is an explicit description of the behaviour required of the system. Methods for conceptual modelling include entity-relationship (ER) modelling, data flow modelling, Jackson System Development (JSD) and several object-oriented analysis methods. Given the current diversity of modelling methods, it is important for teaching as well as using these methods to know what the relationships between them is and to be able to indicate what the (im)possibilities of integrating different methods are. This paper compares three classical modelling methods (ER, data flow, JSD) on their possibilities for integration and combination. It is shown that there is a common core of these methods, which centres around the concept of system transaction and that unifies the static view of a system taken by ER modelling, with the dynamic view taken by JSD and the functional view taken by data flow modelling. Several object-oriented analysis methods integrate these three views. This paper illustrates how this is done in the analysis stage of Object Modelling Technique. Finally, it is shown that the transaction decomposition table can be used as a pivot around which to combine different methods. The results of this paper can be used in teaching to explain the relationships and differences between the methods analysed here, and in system development practice to ease the transition from structured to object-oriented methods.