Table of contents
basic concept
- Data flow diagram is also called data flow diagram (DFD). It gets rid of the physical content of the system and accurately describes the function, input, output and data storage of the system logically. It is an important part of the logical model of the system.
fundamental element
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Data flow: Each data flow uses a well-defined name to reflect the meaning of the data flow [except that it does not need to be named when it flows to or from the data storage]; it is used to indicate the flow direction of the data .
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Processing: Each processing has a name and number; it describes the transformation between the input data stream and the output data stream ; each processing has at least one input data stream and one output data stream.
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Data storage: Each data storage has a well-defined name identification; used to store data .
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External entity: It is used to point out the origin of the data required by the system and the destination of the data generated by the system .
Layering of Data Flow Diagrams
- This approach to structured