4.3 UML And Modeling As Thinking Tools
Modeling is not about producing beautiful diagrams. It is about making a design question visible enough that the team can discuss it.
Use a model when conversation needs a shared object.
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Choose the model for the question
| Diagram | Good question |
|---|---|
| Use case | Who interacts with the system, and what goals matter? |
| Class | What concepts exist, and what responsibilities do they own? |
| Sequence | In what order do objects or services communicate? |
| Activity | What workflow, branch, or exception path exists? |
| State | How does one entity move through states? |
| Component | Which deployable or replaceable parts exist? |
| Deployment | Where does software run, and how does infrastructure connect? |
If nobody knows what decision the diagram supports, stop drawing.
Model the risky part
You usually do not need a complete UML model of the whole system. Model the part with uncertainty:
- A payment retry sequence.
- Account recovery states.
- Role-based access decisions.
- A migration workflow.
- A service boundary before extraction.
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Keep models alive or intentionally disposable
Some models are throwaway thinking tools. Others are living documentation. Decide which one you are making.
Living models should be close to the code, reviewed when decisions change, and simple enough that people actually update them.
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