Functional Diagrams

Overview

Functional diagrams describe systems in terms of processes, data flows, and transformations rather than objects or containers. They answer the question "what does the system do with data?" and "how are functions decomposed into sub-functions?"

This skill covers four complementary functional diagramming techniques:

1. Data Flow Diagrams (DFD) — Show how data moves through a system
2. Functional Decomposition — Break high-level functions into sub-functions
3. IDEF0 — Model decisions, actions, and activities with inputs, controls, outputs, and mechanisms
4. BPMN — Model business processes with standardized notation

Data Flow Diagrams (DFD)

DFDs show how data is processed by a system. They use four core element types and are organized into hierarchical levels.

DFD Elements