The main purpose of DFD is to clarify system requirements and identify major transformations that will be carried out in a system

1. SSAD
DATA FLOW DIAGRAM
Prepared By:
MUKESH MAHTO
MBA-IT

2. DATA FLOW DIAGRAM
• A “Data Flow Diagram” is a graphical representation that
depicts information flow, i.e. it represents the flow of data
between different processes in a business.
• The main purpose of DFD is to clarify system requirements and
identify major transformations that will be carried out in a
system.
• DFDs are used not only in Structured Systems Analysis and
Design but also as a general process modeling tool.
• It is also known as “Bubble Chart”.

3. DFD– Why?
• It gives the summary of the entire system.
• Easy to understand.
• It supports the logic behind the data flow within the system.
• It can also provide a detailed description of the system
components.
• It represents an information system from the viewpoint of data
movements – inputs & outputs.
• It defines the boundaries of the entire system.
• Also, the ability to represent the system at different levels is an
added advantage.
• It parallely shows the relation between a particular process
and its database.

4. Components of DFD
• Various symbols are used in a Data Flow Diagram –
1. - It represents “source” or “destination” of data.
2. - It represents the process that transforms the data
flow.
3. - “Arrow” represents data in motion.
4. - It represents data at rest or database.

5. Levels of DFD
• Level Zero or Context Level DFD – It represents the complete
system with all modules. It is the highest abstraction level DFD.
• Level 1 DFD – The Level 0 DFD is broken down into more
specific i.e. Level 1 DFD. It depicts basic modules in the system
and the flow of data among various modules.
• Level 2 DFD – At this level, DFD shows how data flows inside
the modules mentioned in Level 1.
• Thus, higher level DFDs can be transformed into more specific
lower level DFDs with deeper level of understanding unless the
desired level of specification is achieved.

6. Rules / Good Conventions
• Arrows should have direction as to know where the data
flows.
• Arrows should be labeled as to know what kind of data is
flowing.
• Less number of processes.
• Number the processes.

7. EXAMPLE – Context Level DFD

8. EXAMPLE – Level 1 DFD

9. EXAMPLE – Level 2 DFD

10. THANK YOU