DATA FLOW DIAGRAMS seminars presentation

[seminar class]

presented by:
Mr.Prasad Sawant

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Data Flow Diagrams (DFDs)
• Data flow diagram (DFD) is a picture of the movement of data between external entities and the processes and data stores within a system
DFD Symbols (Gane & Sarson)
Process
• Work or actions performed on data (inside the system)
• Labels should be verb phrases
• Receives input data and produces output
Rule 1: Process
• Can have more than one outgoing data flow or more than one incoming data flow
Rule 2: Process
• Can connect to any other symbol (including another process symbol)
Process: Correct/Incorrect?
Data Store
• Is used in a DFD to represent data that the system stores
• Labels should be noun phrases
Rule: Data Store
Must have at least one incoming and one outgoing data flow
Source/Sink (External Entity)
• External entity that is origin or destination of data (outside the system)
• Is the singular form of a department, outside organisation, other IS, or person
• Labels should be noun phrases
• Source – Entity that supplies data to the system
• Sink – Entity that receives data from the system
Context Diagram
• Top-level view of IS
• Shows the system boundaries, external entities that interact with the system, and major information flows between entities and the system.
• Example: Order system that a company uses to enter orders and apply payments against a customer’s balance