Data flow diagram is usually used to show model the system’s data processing. All the processing steps are shown in the diagram through the system. They are the intrinsic part of the many analysis or design methods. They are modeled to show how the data flow through the system, how the data are flown in the system and how are they related to each other. They also depict how the data are stored at the specific locations in the system. This diagram helps showing how the data are transformed in the system.
Simple and intuitive notations are used for easy understanding showing the end-to-end processing of data. Notations used in this model represents the functional processing (represented by the rounded rectangle), data store (represented by the rectangle )and the data movement between the functions (represented via labeled arrows).
The symbols to define the DFD symbols are given in the given figure:
Generally the data flow models are not supported by the UML as they were supposed to model the data. The reason behind this thing is that the DFDs focuses on the system functions and does not recognize the system objects.