Food Ordering System Context Level DFD
Food Ordering System
Context Level DFD
Symbol Used In Data Flow Diagram (DFD)
Entities: can be people, departments, other companies, other systems… are called sources if they are external to the system and provide data to the system, and sinks if they are external to the system and receive information from the system Processes must have at least one input and at least one output at the primitive level (see below) are labeled with verb + object (e.g. “print invoice” or “add customer”) (e.g. in the hierarchy below, none of the processes are primitive) at the non-primitive level, are labeled more generally (e.g. “customer maintenance” or “warehouse reports”) Data stores: · can be online or “hard copy” (see notes on logical VS physical DFD’s below) · are labeled with a noun (e.g. the label “customer” indicates that information about customers is kept in that data store) · data is stored whenever there are more than one process that needs it and these processes don’t always...
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