Dfd to Structure

DFD to Structure Charts

Georgia State University

DFDs to Structure Charts

First Level Data Flow Diagram
0 Library System

1

Book Catalog

3 2

Borrowers List

Georgia State University

DFDs to Structure Charts

Functional Decomposition
0 Library System 1 2 3

2.1

2.2

Georgia State University

DFDs to Structure Charts

Structure Chart
Structure Chart Example Q: Where do the modules come from?

Logical Design
Executive Module 'Update File' Top because it calls all others none call it at this level

Module 1 e.g. Read

Module 2.. e.g. Update

Module n e.g. Write

Open FIle
Georgia State University DFDs to Structure Charts

Structure Chart
Structure Chart Example Q: Where do the modules come from?

Physical Design

2
Executive Module 'Update File' Top because it calls all others none call it at this level

1

3
Module n e.g. Write

Module 1 e.g. Read

Module 2.. e.g. Update

Open FIle
Georgia State University DFDs to Structure Charts

DFD to Structure Charts?
0 Library System

1

Book Catalog

?
Module 1 e.g. Read Open FIle

Structure Chart Example Q: Where do the modules come from?

3

2

Executive Module 'Update File' Top because it calls all others none call it at this level

Module 2.. e.g. Update

Module n e.g. Write

Borrowers List

Georgia State University

DFDs to Structure Charts

Why Divide Things Up?
Logical Design
– Simplifies understanding
“divide and conquer”

– Allows parallel development

Physical Design
– Separately compilable modules one change should not require a complete build

Georgia State University

DFDs to Structure Charts

Basic Design Goals
Fitness for purpose
– the system must work, and work correctly – it should perform all tasks as specified within the constraints of the resources

Robustness
– the design should be stable against changes to features such as file or data structures

Georgia State University

DFDs