21-04-2011, 04:20 PM
Submitted By:
Kuldeep Singh
[attachment=12582]
DATA FLOW DIAGRAM
A data flow diagram, also known as “bubble chart” has the purpose of clarifying
system requirements and identifying major transformation that will become
programs in system design. It is a graphic representation of a system or portion of
system. A DFD consists of a series of bubbles joined by lines. It consists of data
flows, processes, sources, destinations and stores all described through the use of
easily understood symbols. An entire system can be described from the viewpoint
of the data it processes with only four symbols. The DFD is also powerful enough
to show parallel activities.
TYPES OF DATA FLOW DIAGRAM
• Physical data flow diagram: -Physical data flow diagram is
implementation dependent. They show the actual devices, department,
people etc. involved in the current system.
• Logical data flow diagram: -It describes the system independently of how
it is actually implemented, that is , they show what takes place, rather than
how an activity is accomplished.
COMPONENTS OF DATA FLOW DIAGRAM:
a) Source or Destination: -The source or destination is graphically represented
as a rectangle. Source or destination external entities with which the system
communicates. A source or destination is a person or a group of persons that are
outside the control of the system being modeled.
b) Data Flow: -The flow is represented graphically by an arrow into or out of a
process. The flow is used to describe the movement of chunks or packet of
information from one part of the system to another part. The flow represents data
in motion.
c) Process: -The process shows a part of the system that transforms input into
output. The process is represented graphically as a circle or bubble.
d) Data Store: -The data store is used to model a collection of data packet at rest.
The notation of a data store is two parallel lines. Data stores are typically
implemented as files or databases in computerized system. Data stores are
connected by flow to processes.
Kuldeep Singh
[attachment=12582]
DATA FLOW DIAGRAM
A data flow diagram, also known as “bubble chart” has the purpose of clarifying
system requirements and identifying major transformation that will become
programs in system design. It is a graphic representation of a system or portion of
system. A DFD consists of a series of bubbles joined by lines. It consists of data
flows, processes, sources, destinations and stores all described through the use of
easily understood symbols. An entire system can be described from the viewpoint
of the data it processes with only four symbols. The DFD is also powerful enough
to show parallel activities.
TYPES OF DATA FLOW DIAGRAM
• Physical data flow diagram: -Physical data flow diagram is
implementation dependent. They show the actual devices, department,
people etc. involved in the current system.
• Logical data flow diagram: -It describes the system independently of how
it is actually implemented, that is , they show what takes place, rather than
how an activity is accomplished.
COMPONENTS OF DATA FLOW DIAGRAM:
a) Source or Destination: -The source or destination is graphically represented
as a rectangle. Source or destination external entities with which the system
communicates. A source or destination is a person or a group of persons that are
outside the control of the system being modeled.
b) Data Flow: -The flow is represented graphically by an arrow into or out of a
process. The flow is used to describe the movement of chunks or packet of
information from one part of the system to another part. The flow represents data
in motion.
c) Process: -The process shows a part of the system that transforms input into
output. The process is represented graphically as a circle or bubble.
d) Data Store: -The data store is used to model a collection of data packet at rest.
The notation of a data store is two parallel lines. Data stores are typically
implemented as files or databases in computerized system. Data stores are
connected by flow to processes.
