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C4 and UML
An architectural zoom model and a broader modeling language answer overlapping but different questions.
| Question | C4 model | UML |
|---|---|---|
| Primary job | Choose architectural abstractions and levels | Describe structure and behavior through multiple diagram types |
| Useful first view | System context or container | Sequence, class, activity, or state view according to the question |
| Useful combination | Show the application and its neighbors | Trace one interaction through those participants |
Try the distinction
You have a good system context view but cannot see whether authorization occurs before a data read. What should you add?
Open the reasoning
Add an interaction view, such as a UML sequence diagram, using consistent participant names. More structural boxes will not establish call order.