Data Flow Diagram
12/8/2012
Major Topics
Chapter 9
Using Data Flow Diagrams
Data flow diagram symbols
Data flow diagram levels
Creating data flow diagrams
Physical and logical data flow diagrams
Partitioning
Event driven modeling
Use case and data flow diagrams
Systems Analysis and Design
Kendall and Kendall
Fifth Edition
Kendall & Kendall
Using Data Flow Diagrams
Unexploded data flow diagrams are useful to identify information requirements
Exploded data flow diagrams can be used for presentation, education, and gathering feedback information from users
Copyright © 2002 by Prentice Hall, Inc.
9-3
One of the main methods available for analyzing data-oriented systems
DFDs emphasize the logic underlying the system
The systems analysts can put together a graphical representation of data movement through the organization
Copyright © 2002 by Prentice Hall, Inc.
DFDs may be used to analyze the system to ensure that the design is complete DFDs are used to partition the system into programs
Data flow diagrams can be used for the system documentation
Kendall & Kendall
Copyright © 2002 by Prentice Hall, Inc.
9-4
Advantages of the Data Flow
Diagram Approach
Data Flow Diagrams
Kendall & Kendall
9-2
Using Data Flow Diagrams
Data flow diagrams can be used for several different purposes:
Kendall & Kendall
Copyright © 2002 by Prentice Hall, Inc.
9-5
Four advantages over narrative explanations of data movement
Freedom from committing to the technical implementation too early
Understanding of the interrelationships of systems and subsystems
Communicating current system knowledge to users
Analysis of the proposed system
Kendall & Kendall
Copyright © 2002 by Prentice Hall, Inc.
9-6
1
12/8/2012
Basic Symbols
External Entities
Four basic symbols are
A double square for an external entity--a source or destination of data
An arrow for movement of data from one point to another
Major Topics
Chapter 9
Using Data Flow Diagrams
Data flow diagram symbols
Data flow diagram levels
Creating data flow diagrams
Physical and logical data flow diagrams
Partitioning
Event driven modeling
Use case and data flow diagrams
Systems Analysis and Design
Kendall and Kendall
Fifth Edition
Kendall & Kendall
Using Data Flow Diagrams
Unexploded data flow diagrams are useful to identify information requirements
Exploded data flow diagrams can be used for presentation, education, and gathering feedback information from users
Copyright © 2002 by Prentice Hall, Inc.
9-3
One of the main methods available for analyzing data-oriented systems
DFDs emphasize the logic underlying the system
The systems analysts can put together a graphical representation of data movement through the organization
Copyright © 2002 by Prentice Hall, Inc.
DFDs may be used to analyze the system to ensure that the design is complete DFDs are used to partition the system into programs
Data flow diagrams can be used for the system documentation
Kendall & Kendall
Copyright © 2002 by Prentice Hall, Inc.
9-4
Advantages of the Data Flow
Diagram Approach
Data Flow Diagrams
Kendall & Kendall
9-2
Using Data Flow Diagrams
Data flow diagrams can be used for several different purposes:
Kendall & Kendall
Copyright © 2002 by Prentice Hall, Inc.
9-5
Four advantages over narrative explanations of data movement
Freedom from committing to the technical implementation too early
Understanding of the interrelationships of systems and subsystems
Communicating current system knowledge to users
Analysis of the proposed system
Kendall & Kendall
Copyright © 2002 by Prentice Hall, Inc.
9-6
1
12/8/2012
Basic Symbols
External Entities
Four basic symbols are
A double square for an external entity--a source or destination of data
An arrow for movement of data from one point to another