Defining DFD Components

DFDs consist of four basic components:-

Entity:- An entity is the source or destination of data. Entities either provide data to the system or receive data from it. Entities are often represented as rectangles.

Process: -

The process is the manipulation or work that transforms data, performing computations, making decisions (logicflow), or directing data flows based on business rules. In other words, a process receives input and generates some output. Processes can be drawn as circles or a segmented rectangle on a DFD, and include a process name and process number.

Data Store:- Collection of data that is pemanently stored. Data stores are usually drawn as a rectangle with the righthand side missing.

 

Data Flow:- Data flow is the movement of data between the entity,
the process, and the data store. Data flow is represented by an arrow,
where the arrow is annotated with the data name.