Rules to Draw DFD
Rules to Draw DFD :
Arrows should not cross each other.
Squares, circles and files must have names.
Draw all data flows squares or circles can have the name .
Choose the meaningful names for data flows process and data stores.
Decomposed data flows must be balanced.
Types of data flows diagram -
There are two types of data flow
diagram are given below -
1. Physical DFD
2. Logical DFD
Physical DFD : It
shows the actual implementation and movement of data between people,
departments and work stations. A n implementation departments view of the
current system showing what talk are carried include in physical DFD are as
follows-
Name of the people departments name masters and
transaction files , equipment and devices use location etc.
Advantage: Physical DFD is useful for communication
with uses and provides a ways to validate users current view of the system.
Logical DFD : The transformation of data from input to
output through process may be described logically and independently of the
physical comportment (computer, file cabinets ,disk unit etc) associated with
the systems. An implementation independent view the system ,focusing on the
flow of data between process with out required for the specifies devices
storage location or people in the system.
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