SDM 5 - Introduction to Data Flow Diagram

Question 1

What is the purpose of data flow diagram?

Answer 1

• To show how the system interacts with the external entities, as well as databases
• To show the processes that data undergo in a system
• To show how data moves and changes through an information system in a graphical, top-down fashion

Question 2

Why do we choose DFD?

Answer 2

DFDs reperesent data flow in a logical way, meaning it does not constrict the implementation of the data flow
DFDs also do not distinguish manual or automated processes

Question 3

what are the components of DFD?

Answer 3

External entities / Source & sink
Process
Data flow
Data store

Question 4

What do external entities represent?

Answer 4

Person, department, outside organization, outside information system that provides or consumes the data

Question 5

What does process represent?

Answer 5

Transforms input into output

Question 6

What does data flow represent?

Answer 6

Transfer of data among data stores, sources or sinks, processes

Question 7

what do data store represent?

Answer 7

Data repository

Question 8

What is a context diagram?

Answer 8

A top level diagram that graphically defines the system boundary and the flow of data between the system and external entities

Question 9

Give one example of DFD

Answer 9

Yourdon/DeMarco context diagram

Question 10

What are the key characteristics of the context diagram?

Answer 10

Only 1 process
The relationship between the external entities and the system is drawn around the perimeter
No data store drawn
entities are connected to the process with data flow
No direct connection between 2 entities

Question 11

Is the DFD useful?

Answer 11

It assist a system analyst in graphically conceptualizing and visualizing data transformation from input to output in a system