Data Flow

DATA FLOW DIAGRAM - one of the most commonly used modeling tool which graphically represents a system as a network of processes, linked together through input and output flow lines and entities.

Data flow Components ▪ Process - transformation of data flow into outgoing data flow. It may represent . . - whole system - subsystem - activity

▪ Data store - repository of data in the system It may represent . . . - computer file or database - A transaction file - A set of tables - A manual file of records

▪ Data flow - pipeline which represents the movement of data from one point to another - shows the data about a person, place, or thing that moves through the system

▪ Entity - source or destination of input and output - represent people or organizations outside of the system being studied - shows the initial source and final recipient of data and information It maybe . . . - person – e.g. EMPLOYEE, STUDENT, etc - company or organization – e.g. SCHOOL, BANK, etc - Another department within the company – e.g. HUMAN RESOURCE DEPARTMENT, SALES DEPARTMENT, etc. - Another system or subsystem – ACCOUNTING SYSTEM, FACULTY LOADING SYSTEM, etc

Data flow Notations

|DFD COMPONENTS |YOURDON & COAD |GANE & SARSON |
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|Process | | |
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|Data store | |