Data Flow Diagram (DFD)

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What is a Data Flow Diagram?

 

A data flow diagram (DFD) is a graphical representation of the flow of data between processes.

In other words, it shows:

  • What goes in

  • How it is changed

  • What comes out

 

The following symbols are generally used:

 

  • Data flow is represented by a labelled arrow

  • Processes are represented by labelled circles (bubbles)

  • Information sources and sinks are represented by boxes

  • Files are represented by a double line

 

For further guidance and examples, see:

http://www.dragonstrike.com/icleal/dfd/index.htm 

http://www.smartdraw.com/resources/centers/software/dfd.htm

http://www.wa.gov/dis/jin/comdataarch/data.htm 

http://www.studyict.com/alevelict/data_flow_diagram.htm 

http://www.dcs.bbk.ac.uk/~steve/2_2/index.htm 

Takeaway Restaurant

Draw your own DFDs with SmartDraw

 

Chinese Takeaway

The example below is an illustration of the data flow in a takeaway restaurant.  The order is taken on a carbon pad, the cost is calculated from the menu, the order is checked with the customer, if OK the order is stuck on a pin-board.  When the food is ready, the order becomes the delivery note for the driver.  At the close of business, carbons are used to update accounts and then dumped along with the delivery notes.  Management information is passed to the manager.

Download this DFD as a PowerPoint Presentation