Lecture 3: Introducing Data Flow Diagrams (DFDs). Section 1 - The Concept of Diagrams Why use Diagrams? Diagrams as Working Documents Systems Analysis Modelling Techniques. Why Use Diagrams?. To help overcome the communication problem between users and developers.
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Section 1 - The Concept of Diagrams
DEVELOPERS (have discussions with users etc)
CREATE DIAGRAMS (to record understanding)
AMEND DIAGRAMS (with further information)
USE DIAGRAMS as the
BASE OF SYSTEM STRUCTURE
Section 2 - Data Flow Diagrams (DFDs)
A process may be defined as an action or series of
actions which produce a change or development.
A DFD has four key components.
Processes transform input into output.
Write data to a file
Take data from a file