Context DiagramsContext Diagrams

There are three symbols used in these diagrams:

Context Diagrams are used in the Analysis and Design phases as an analysis and design tool used to analyse processes occurring in a current information system and also to design a new information system.

They help in identifying where problems may be occurring in an information system.

Data FlowData Flow

Data flows describe the data being transferred, not the processing of the data.

E.g. “booking” is used rather than “validate booking”.

“Validate booking” is a process whereas the “booking” itself is the data.

Booking

The whole system and a processThe whole system and a process

The oval shape is used to represent the whole information processing system (Context Diagram)

Booking system

The whole system

External EntityExternal Entity

People, programs, organisations, other info systems that provide data to the system or receive output from the system.

Nouns are used to name external entities.External entities are things that are external

to the system in question.

students

Context DiagramsContext Diagrams

The highest level of the data flow diagram.

General description of the system and its relationship with “the outside world.”

Restaurant System SuppliersDiners

Bookings

Orders

Invoice

Payment