Context Diagrams There are three symbols used in these diagrams: Context Diagrams are used in the...
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Transcript of Context Diagrams There are three symbols used in these diagrams: Context Diagrams are used in the...
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