Definition, Prototyping, and Reviews Flashcards
Involves formally spelling out the requirements
Requirements Definition
what is DFD
Data Flow Diagram
What is ERD
Entity-Relationship Diagram
DFD was introduced in what year
1970s
DFD was introduced by
DeMarco,Gane, Sarson
ERD was introduced in what year
1976
ERD was introduced by
Peter Chen
A graphical tool, useful for communicating with
users, managers, and other personnel.
DFD
DFD is used to perform ______ to determine logical requirements
structured analysis
DFD focuses on _____
movement of data between external entities and processes, and between processes and data stores
DFD provides an overview of
Data system processes, transformations performed, data storage, production of results and their flow
people or organisations that send data
into the system or receive data from the system
External Entity
models what happens to the data
i.e. transforms incoming data into outgoing data
Process
represents permanent data that is used by
the system
Data Store
models the actual flow of the data between
the other elements
Data Flow
Context Diagram
Level 0
Contains only one process
Level 0
represents entire system
Level 0
Data arrows show input output
Level 0
Data stores are NOT shown, they are within the system
Level 0
The major information flows between the entities
and the system
Level 0
Level ____ must balance with the context diagram it
describes
Level 1
Input going into a process are different from outputs
leaving the process.
Level 1
Data stores are first shown at this level
Level 1
