DATA

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Data Flow Diagram

A data flow diagram (DFD) illustrates how data is processed by a system in terms of inputs and outputs. As its name indicates its focus is on the flow of information, where data comes from, where it goes and how it gets stored.

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History of Data Flow Diagrams

Data flow diagrams became popular in the 1970s in software development. They were first described in a classic text about Structured Design written by Larry Constantine và Ed Yourdon. Yourdon và Coad"s Object Oriented Analysis and Design (OOA/OOD) was a way of visualizing software systems before UML diagrams.

Data Flow Diagram Tutorial

donghocititime.com contains all the needed data flow diagram symbols & easy-to-use templates that help you get started. Stamp shapes to your drawing area & connect them easily with keyboard shortcuts or intuitive sầu commands located on the SmartPanel to the left of your drawing area.

You can even nest different levels of data flow diagrams by using donghocititime.com"s hyperlink function.

Learn more by reading this tutorial on making data flow diagrams.


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Data Flow Diagrams Symbols

There are essentially two different types of notations for data flow diagrams (Yourdon và Coad or Gane & Sarson) defining different visual representations for processes, data stores, data flow & external entities.

Yourdon and Coad type data flow diagrams are usually used for system analysis & thiết kế, while Gane and Sarson type DFDs are more comtháng for visualizing information systems.

Visually, the biggest difference between the two ways of drawing data flow diagrams is how processes look. In the Yourdon & Coad way, processes are depicted as circles, while in the Gane và Sarson diagram the processes are squares with rounded corners.

Process Notations. A process transforms incoming data flow into outgoing data flow.

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Datastore Notations.

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Datastores are repositories of data in the system. They are sometimes also referred khổng lồ as files.

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Dataflow Notations. Dataflows are pipelines through which packets of information flow. Label the arrows with the name of the data that moves through it.

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External Entity Notations. External entities are objects outside the system, with which the system communicates. External entities are sources và destinations of the system"s inputs & outputs.

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Data Flow Diagram Levels

Context Diagram. A context diagram is a top level (also known as "Level 0") data flow diagram. It only contains one process node ("Process 0") that generalizes the function of the entire system in relationship to lớn external entities.

DFD Layers. Draw data flow diagrams can be made in several nested layers. A single process node on a high level diagram can be expanded khổng lồ show a more detailed data flow diagram. Draw the context diagram first, followed by various layers of data flow diagrams.

DFD Levels. The first cấp độ DFD shows the main processes within the system. Each of these processes can be broken inkhổng lồ further processes until you reach pseubởi vì code.

Data Flow Diagram Examples


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Warehouse Cycle Count Data Flow Diagram
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Data Flow - Insurance Claims