Data flow diagrams (DFDs) are used to model systems and show how input data is transformed into output through a series of functional steps. DFDs reveal relationships between different components in a program or system. They have four main elements - entities, processes, data stores, and data flows. Entities represent external sources or recipients of data, processes perform functions to transform data, data stores hold data between processes, and data flows show the movement of data between elements.

3. DFD
DFDs are an
important technique
for modeling a
system’s high-level
detail by showing
how input data is
transformed to output
results through a
sequence of
functional
transformations
Data flow
diagrams (dfds)
reveal
relationships
among
and between the
various
components in a
program or system

4. WHAT ARE DATA FLOW DIAGRAMS?

6. DATA FLOW DIAGRAMS

7. DATA FLOW DIAGRAMS

8. DFD
Four major components
Entities Processes
Data
stores
Data
flows

9. Entity
•An entity is the source or destination of data.
•The source in a DFD represents these entities that
are outside the context of the system.
• Entities either provide data to the System or
receive data from it.
• Entities are often represented as rectangles.

10. Process

11. Data Store
•A data store is where a process stores data between
processes for later retrieval by that same process or
another one. Files and tables are considered data stores.
•Data store names are simple but meaningful,
such as “customers,” “orders,” and “products.”
•Data stores are usually drawn as a rectangle with the right
hand side missing and labeled by the name of the data
storage area it represents, though different notations do exist.

12. Data Flow

13. Symbols used to depict how these components
interact in a system are simple and easy to understand;
however, there are several DFD models to work from,
each having its own symbology

14. CONCLUSION