DFD stands for Data Flow Diagram. It is an important tool used by system analysts. The flow of data of a system or a process is represented by DFD. A data flow diagram is a visual representation of how data flows within a system. DFD is a modelling technique that is used to analyze, design and document the flow of data in a system.
It is a graphical representation of the flow of data through a system, which helps to identify the inputs, outputs and processes involved in the system. It can be used to represent a system in terms of the input data to the system, various processing carried out on those data, and the output data generated by the system.
In nutshell, data flow diagrams simply provide a visual representation of how data is handled in a system. The main merit of DFD is that it can provide an overview of what data a system would process, what transformations of data are done, what files are used and where the results flow. The graphical representation of the systems makes it a good communication tool between a user and analyst. DFDs are structured in such a way that starting from a simple diagram which provides a broad overview at a glance, they can be expanded to hierarchy of diagrams giving more and more detail. The data flow diagram provides information about the process itself, outputs and inputs of each entity, and the various sub processes the data moves through.
Components of DFD:
DFD mainly consists of four main components. The components are :
External Entities: A external entity is a source or destination of data that is outside the system being modelled. An external entity represents as person, organization or system that interacts with the system. It is usually are represented by a rectangle with their respective names.
Process: A process represents a specific action or function within the system that transforms input data into output data. Processes are represented by circles in a DFD.
Data stores: A data store represents a repository of data that is maintained by the system. it can be a physical location such a s a cloud storage service. It usually represented as an open rectangle.
Data Flow: A data flow represents the movement of data from one process to another or from a process to a data store. Data flows are represented by arrows in a DFD.
