The diagram
Every HTTP response is a decision.
Send a request from the rail, or call this page's live URL with curl, and watch the flowchart decide the status one question at a time.
WebMacha sandbox
The client wants to overwrite version "v1" and says so with If-Match, but the resource is now at "v2". At G11 the tags do not match, so the PUT is refused with 412 rather than silently overwriting someone else's change.
Decision flow
Decision path
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Request log
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