Data-flow diagram

The notation presented above was described in 1979 by Tom DeMarco as part of structured analysis.

The data-flow diagram is a tool that is part of structured analysis and data modeling.

Data-flow diagrams can be regarded as inverted Petri nets, because places in such networks correspond to the semantics of data memories.

Analogously, the semantics of transitions from Petri nets and data flows and functions from data-flow diagrams should be considered equivalent.

[3] It was first proposed by Larry Constantine,[4] and popularized by Edward Yourdon, Tom DeMarco,[5] Chris Gane and Trish Sarson,[6][7] who enriched the diagramming technique with different notations, data dictionary practices[5] and guidance for the hierarchical decomposition of processes.

[6] The primary aim of data-flow diagrams in the context of structured design was to build complex modular systems, rationalizing the interdependencies across different modules.

[3] Data-flow diagrams (DFD) quickly became a popular way to visualize the major steps and data involved in software-system processes.

DFDs were usually used to show data flow in a computer system, although they could in theory as well be applied to business process modeling.

The process is named in one word, a short sentence, or a phrase that is clearly to express its essence.

The arrow shows the flow direction (it can also be bi-directional if the information to/from the entity is logically dependent—e.g.

The symbol of the store is two horizontal lines, the other way of view is shown in the DFD Notation.

The warehouse is represented by two parallel lines between which the memory name is located (it can be modeled as a UML buffer node).

It is determined for system developers, on one hand, project contractor on the other, so the entity names should be adapted for model domain or amateur users or professionals.

For a clear overview of the entire DFD hierarchy, a vertical (cross-sectional) diagram can be created.