In this blog I will explains the Data Flow Diagram’s objects.
It is an activity which transforms and manipulates input data to produce output data.
A flow communicates data between processes, external entities, and data stores. It symbolizes data in motion, which can be computerized components, such as messages or bits, or non-computerized components.
A data store is the place where data exist in permanently or temporarily. It replies to requests for storing and retrieving data, but cannot initiate any actions. It stands for data at rest, which can be computerized components, such as files or databases, or non-computerized components.
An external entity conveys or receives data from the system. It can represent a person, a machine, an organization etc., that is external to the system being modeled. Flows outgoing from external entities go to processes.
Data Flow Diagram Balancing
The concept of balancing states that all the incoming flows to a process and all the outgoing flows from a process in the parent diagram should be preserved at the next level of decomposition.