SA/D Topic 5 -- Data Flow Diagrams


Data Flow Diagrams


Requirements Determination


Advantages of Graphical Depiction


Current Logical System


System Progression


Symbols

Square

Arrow

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