Methods & retry safety
04Reading, replacing, processing, and deleting have different semantics, especially after a connection fails.
Related RFCs and changes
“Updates” changes part of an earlier RFC. “Obsoletes” replaces it. This list shows selected related documents.
DIAGRAM§ 9 ↗
RFC 9110 · § 9EXAMPLE
4 / 4
04
Avoid accidental duplicate effects.
A missing response does not prove that the server did nothing.
Protocol participantThreat or exceptionProtocol controlSimplified drawings · precise section references
Read the updated RFC section ↗
Retry according to semantics and evidence.
- GET and HEAD retrieve information; HEAD omits response content. Safe methods do not request state changes.
- PUT replaces target state, POST requests target-specific processing, and DELETE removes the target association. PUT and DELETE are idempotent.
- OPTIONS describes communication options, CONNECT establishes a tunnel, and TRACE requests a loopback diagnostic.
Idempotent means repeating the intended effect is equivalent to one request. Responses can differ. Automatically retrying a non-idempotent request requires knowledge that doing so is safe or that the original was not applied.
Read the RFC section ↗Diagrams simplify the RFC. Read the linked sections for complete requirements.
Privacy