Data Flow Diagram - How to develop DFD

Developing Data Flow Diagrams

The most comprehensive and useful approach to developing an accurate and complete description of the current system begins with the development of a physical data flow diagram. The use of physical data flow diagrams is desirable for three reasons:

1.   Analysts initially find it easier to describe the interaction between physical components than to understand the policies used to manage the application. Identifying people, what they do, which documents and forms trigger which activities and what equipment is used in the processing. The movement of people, documents and information between departments and locations is also identified.

2.   Physical data flow diagrams are useful for communicating with users. Users relate easily to people, locations and documents as they work with these each day. Users may consider logical DFDs abstract as they do not contain these familiar components, however, with physical DFDs users can quickly identify incorrect or missing steps.

3.   Physical DFDs provide a way to validate or verify the user's current view of the system with the way it is actually operating. If there are differences, they will be noted and discussed. It is not unusual to find that what a users thinks is happening differs in an important way from what actually occurs.