ABSTRACT

Graphical Tools DFD and IDEF0 are commonly used graphical tools for modeling the Behavioral Model. Each also has provisions for modeling the context diagram of the Environmental Model. DFD supports activity and functional modeling by first focusing on what data is flowing through the system. Activities and functions are therefore defined by the need to transform data from one form into another. The points of transformation identified in this way become the nodes of the DFD graph. Data is the only entity associated with the nodes in DFD, and the nodal semantics express only whether data is flowing into a node or out of it or is being stored by the node. IDEF0 is graphically similar in form, although the semantics of graphical representation of the nodes differ somewhat from the DFD semantics; in

some ways, IDEF0 is richer. Practitioners of IDEF0 also tend to focus more on the nodes than on the data flow. Both of these graphical tools are used in the practice of functional modeling of information-intensive systems, but the differences in their nodal semantics preclude full exchange of information between a DFD and an IDEF0 graph.