3. EXP-2.3: Data Flow Diagram
INTRODUCTION:
Data Flow Diagram (DFD) represents the flow of
data within information systems.
Data Flow Diagrams (DFD) provide a graphical
representation of the data flow of a system that can
be understood by both technical and non-technical
users.
The models enable software engineers,
customers, and users to work together effectively
during the analysis and specification of
requirements.
4. EXP-2.3: Data Flow Diagram
INTRODUCTION:
What is Data Flow Diagram?
It is a graphical tool, useful for communicating
with users, managers and other personnel.
It is useful for analyzing existing as well as
proposed Systems.
It provides an overview of
– What data is system processes.
– What transformation are performed.
– What data are stored.
– What results are produced , etc.
5. EXP-2.3: Data Flow Diagram
Characteristics of Data Flow Diagram (DFD):
• Graphical Representation: Data Flow Diagram
(DFD) use different symbols and notation to
represent data flow within system. That simplify
the complex model.
• Problem Analysis: Data Flow Diagram (DFDs) are
very useful in understanding a system and can be
effectively used during analysis.
Data Flow Diagram (DFDs) are quite general
and are not limited to problem analysis for
software requirements specification.
6. EXP-2.3: Data Flow Diagram
Characteristics of Data Flow Diagram (DFD):
• Abstraction: Data Flow Diagram (DFD) provides a
abstraction to complex model i.e.
DFD hides unnecessary implementation
details and show only the flow of data and
processes within information system.
• Hierarchy: Data Flow Diagram (DFD) provides a
hierarchy of a system.
High- level diagram i.e. 0-level diagram
provides an overview of entire system while lower-
level diagram like 1-level DFD and beyond provides
a detailed data flow of individual process.
7. EXP-2.3: Data Flow Diagram
Characteristics of Data Flow Diagram (DFD):
• Data Flow: The primary objective of Data Flow
Diagram (DFD) is to visualize the data flow
between external entity, processes and data
store.
Data Flow is represented by an Arrow Symbol.
• Ease of Understanding: Data Flow Diagram (DFD)
can be easily understand by both technical and
non-technical stakeholders.
8. EXP-2.3: Data Flow Diagram
Characteristics of Data Flow Diagram (DFD):
• Modularity: Modularity can be achieved using
Data Flow Diagram (DFD) as it breaks the complex
system into smaller module or processes.
This provides easily Analysis and Design of a
system.
9. EXP-2.3: Data Flow Diagram
Types of Data Flow Diagram (DFD):
There are two types of Data Flow Diagram (DFD)
–Logical Data Flow Diagram
–Physical Data Flow Diagram
10. EXP-2.3: Data Flow Diagram
(A)Logical Data Flow Diagram:
Logical data flow diagram mainly focuses on
the system process. It illustrates how data flows in
the system.
Logical Data Flow Diagram (DFD) mainly focuses on
high level processes and data flow without diving deep
into technical implementation details.
Logical DFD is used in various organizations for the
smooth running of system.
Like in a Banking software system, it is used to
describe how data is moved from one entity to another.
12. EXP-2.3: Data Flow Diagram
(B) Physical Data Flow Diagram
Physical data flow diagram shows how the data
flow is actually implemented in the system.
In the Physical Data Flow Diagram (DFD), we
include additional details such as data storage, data
transmission, and specific technology or system
components.
Physical DFD is more specific and close to
implementation.
15. EXP-2.3: Data Flow Diagram
Levels of Data Flow Diagram (DFD):
Data Flow Diagram (DFD) uses hierarchy to maintain
transparency thus multilevel Data Flow Diagram (DFD’s) can be
created. Levels of Data Flow Diagram (DFD) are as follows:
17. EXP-2.3: Data Flow Diagram
1-Level DFD
This level provides a more detailed view of the
system by breaking down the major processes
identified in the level 0 DFD into sub-processes.
Each sub-process is depicted as a separate process
on the level 1 DFD. The data flows and data stores
associated with each sub-process.
In 1-level DFD, the context diagram is decomposed
into multiple bubbles/processes.
In this level, we highlight the main functions of the
system and breakdown the high-level process of
0-level DFD into subprocesses.
19. EXP-2.3: Data Flow Diagram
Advantages of Data Flow Diagram (DFD)
It helps us to understand the functioning and the
limits of a system.
It is a graphical representation which is very easy
to understand as it helps visualize contents.
Data Flow Diagram represent detailed and well
explained diagram of system components.
It is used as the part of system documentation file.
Data Flow Diagrams can be understood by both
technical or nontechnical person because they are
very easy to understand.
20. EXP-2.3: Data Flow Diagram
Disadvantages of Data Flow Diagram (DFD):
At times Data Flow Diagram (DFD) can confuse the
programmers regarding the system.
Data Flow Diagram takes long time to be
generated,
and many times due to this reasons analysts are
denied permission to work on it.
21. EXP-3: Data Flow Diagram
How to Draw Data Flow Diagram?
Following are the steps to Draw Data Flow Diagram
