What is DFD(Data Flow Diagram)?
DFDis the abbreviation forData Flow Diagram.
The flow of data of a system or a process is represented by DFD. It
also gives insight into the inputs and outputs of each entity and the
process itself. DFD does not have control flow and no loops or decision
rules are present. Specific operations depending on the type of data
can be explained by a flowchart.
It is a graphical tool, useful for communicating with users ,managers
and other personnel. it is useful for analyzing existing as well as
proposed system.
It provides an overview of
What data is system processes.
What transformation are performed.
What data are stored.
What results are produced , etc.
Data Flow Diagram can be represented in several ways. The DFD
belongs to structured-analysis modeling tools. Data Flow diagrams are
very popular because they help us to visualize the major steps and data
involved in software-system processes.
Rules for creating DFD
The name of the entity should be easy and understandable without
any extra assistance(like comments).
The processes should be numbered or put in ordered list to be
referred easily.
The DFD should maintain consistency across all the DFD levels.
A single DFD can have a maximum of nine processes and a
minimum of three processes.
Symbols Used in DFD
Square Box:A square box defines source or destination of the
system. It is also called entity. It is represented by rectangle.
Arrow or Line:An arrow identifies the data flow i.e. it gives
information to the data that is in motion.
