Data flow diagrams are an integral part of any software development design phase. The purpose and value of the data flow diagram is primarily data discovery, not process mapping - hence the name "data flow diagram" (DFD).The pioneers of structured analysis and design methods - Gane and Sarson, DeMarco - devised their DFD approaches to formalize analysts' anecdotal and idiosyncratic data safaris. When a search is launched for raw data with which to populate a model, the DFD provides the cage to bring it back alive. Data items thus discovered are cataloged in a data dictionary, then subjected to algorithms for normalization and aggregation into entities of a data model or entity-relationship diagram.

To get a better understanding as to how a Data Flow Diagram can be used to understand the flow of data, let us look at some sample diagrams.


Claims Processing - Yourdon and Coad Diagram            
   

Generic - Yourdon and Coad Diagram

Quiz Software - Yourdon and Coad Diagram

Course Registration - Gane and Sarson Diagram

Data downloaded from http://www.smartdraw.com
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