History of DFD
Data Flow Diagram was invented by Larry Constantine, who developed the Structured Design Concept based on Martin and Estrin's "Data Flow Graph" model of computation. In the traditional Application development environment, most of the System Analyst and Application Designer implemented "Structured Systems Analysis and Design Methodology - SSAAD" with Data Flow Diagram, Logical Data Structure and Entity Life History Diagram.
Data Flow Diagram is a Process Oriented Graphical Method to re-present an Organization Business with Process, Data Storage, Data Flow and External Entity Information. Logical Data Structure is a Data Oriented Graphical Method to re-present Data File Information about Data File Types, Data File Attributes and Data File Relationship Information. Entity Life History Diagram is a Event Oriented Graphical Method to re-present each Business External Entity Life Information about when Entity Data Insert, Update or Delete in the Data File.
A Business System can recognize from the Business Process, Business Policy and Business Transaction Data. In the traditional Application development environment from 1960 to 1970, the Application Code and Business Information was store in the Flat File Method. However, a Legacy Application System can recognize from the Application Process, Application Code and Application Data File.
At present, most of the Business, System, Functional and Data Analyst are implement this Data Flow Diagram Concept in their System Specification Document to transform their recognized Business and Application Functional Information to the Business Management Team and Application End User. An approved Data Flow Diagram should help to design a Functional and Data Architecture.
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