SA/D Topic 5 -- Data Flow Diagrams

Data Flow Diagrams

Requirements Determination

Advantages of Graphical Depiction

Current Logical System

System Progression




Circle or Round-edged rectangle

Open-ended rectangle


Developing Data Flow Diagrams

Steps in developing a DFD:

Context Diagram

Diagram 0  


Tips for Creating DFDs

Because a data flow diagram is two-dimensional rather than linear, you can start at any point and work forward or backward through the diagram.

More Detailed DFD Levels

Choosing Level of Detail

Common Errors (fig 9.5, 9.6) p249-250




A correct DFD

Logical DFDs

Physical DFDs

Reasons for Physical DFD

Read "Event Modeling and Data Flow Diagrams" p 258-259

Read "Use Cases and Data Flow Diagrams" p 260

Read "Partitioning" p 260-263

See video store example p 263-270