Explain in detail about Functional Modeling.

• This model explains the computations that take place within a system.
• This model is useful when the transformation from the inputs to outputs is difficult.
• The functional model of a system can be shown by a data Flow Diagram (DFD).

Data Flow Diagrams/Data Flow Graph/Bubble chart

• A DFD is a graphical representation that depicts the information flow and the transforms that are applied as the data move from input to output.
• Level 0 DFD also known as fundamental system model or context model shows the entire software as a single bubble with input and output data shown by incoming and outgoing arrows.
• Level 1 DFD contains 5 or 6 bubbles. Every bubble can be refined at Layers to depict more details.

Extensions to Real Time Systems

• Hatley and Pirbhai extension.
• Ward and Meller extensions