Editing Data-flow diagram (section)

{{Short description|Graphical representation of the "flow" of data through an information system}}
[[File:Data-flow-diagram-example.svg|alt=Data flow diagram with data storage, data flows, function and interface|thumb|478x478px|Data flow diagram with data storage, data flows, function and interface]]
A '''data-flow diagram''' is a way of representing a flow of data through a [[process]] or a system (usually an [[information system]]). The DFD also provides information about the outputs and inputs of each entity and the process itself. A data-flow diagram has no control {{nowrap|flow{{tsp}}{{mdash}}{{tsp}}there}} are no decision rules and no loops. Specific operations based on the data can be represented by a [[flowchart]].<ref name=":0">{{Cite journal|last1=Bruza|first1=P. D.|last2=van der Weide|first2=Th. P.|date=1990-11-01|title=Assessing the quality of hypertext views|journal=ACM SIGIR Forum|volume=24|issue=3|pages=6–25|doi=10.1145/101306.101307|s2cid=8507530|issn=0163-5840}}</ref>

There are several notations for displaying data-flow diagrams. The notation presented above was described in 1979 by [[Tom DeMarco]] as part of [[structured analysis]].

For each data flow, at least one of the endpoints (source and / or destination) must exist in a process. The refined representation of a process can be done in another data-flow diagram, which subdivides this process into sub-processes.

The data-flow diagram is a tool that is part of [[structured analysis]], [[data modeling]] and [[threat modeling]]. When using [[Unified Modeling Language|UML]], the [[activity diagram]] typically takes over the role of the data-flow diagram. A special form of data-flow plan is a site-oriented data-flow plan.

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.