Explaining the Full UML Diagram Suite to Model Users
What the domain tests
This domain tests whether you can select and explain the right UML 2.5 diagram for a stakeholder question. You need the full suite: structure diagrams (Class, Object, Package, Composite Structure, Component, Deployment, Profile) and behavior diagrams (Use Case, Activity, State Machine, Interaction-Sequence, Communication, Timing, Interaction Overview-and Protocol State Machine).
Core rules
- Match the diagram to the question. Class: static types and relationships. Object: instance snapshot with slots. Package: namespace dependencies. Composite Structure: internal parts, ports, connectors. Component: provided and required interfaces. Deployment: artifacts on nodes. Profile: stereotype extensions.
- Behavior: Use Case for scope; Activity for control and data flow; State Machine for lifecycle; Sequence for time-ordered messages; Communication for links and message numbering; Timing for state changes against time; Interaction Overview for control flow among interactions; Protocol State Machine for interface order.
- Explain notation as a contract: an arrow, a port, or a state means something specific; do not mix structural and behavioral intent.
Worked example
For a login feature, show a Use Case for scope, a Sequence for the message exchange between actor, UI, and authentication service, a State Machine for the session lifecycle, a Deployment for the authentication server, and a Class diagram for Credential and Session. Reasoning: each view answers a different question-scope, order, lifecycle, allocation, static data-and none replaces the others.
Traps
Sequence is not for static structure; Communication emphasizes links, not strict time order; Timing is not a Sequence with a timeline only; Interaction Overview is not a Sequence with frames for its own sake. Profile is structural, not behavioral. Object diagrams show instances and slots, not classes. Do not call every diagram a "flowchart".