Stage 2: Requirements Specification

Data Flow Diagram (DFD) Tips

Processes: Verbs Dataflows: Nouns Data Stores: Nouns External Entities: Nouns

1) Process’s input & output are different 2) Each data store should have at least one data flow in and one data flow out 3) Each process should have at least one data flow in and one data flow out 4) All inputs and outputs should be labeled 5) Processes should have an identifier (Ex., 1.0, 2.0, etc.)

Process Process

Process-to-Process

Process Process

Process-to-Process

Process-to-External Entity

Process External

Entity

Process-to-External Entity

Process External

Entity

Data S tore

Process-to-Data Store

Process Data S tore

Process-to-Data Store

Process

External Entity-to-External Entity

External Entity

External Entity

External Entity-to-External Entity

External Entity

External Entity

Data S tore

Data Store-to-Data Store

Data S toreData S tore

Data Store-to-Data Store

Data S tore

External Entity-to-Data StoreExternal Entity-to-Data Store

External Entity

Data S tore External

Entity Data S tore

External Entity

Data S tore

External Entity-to-Data Store

External Entity

Data S toreProcess Process

Process-to-Process

Process-to-External Entity

Process External

Entity

Data S tore

Process-to-Data Store

Process

External Entity-to-External Entity

External Entity

External Entity

Data S tore

Data Store-to-Data Store

Data S tore

External Entity-to-Data Store

External Entity

Data S tore