Keep caching and retirement separate
02Cache policy governs reuse of a representation; Sunset describes expected resource availability and says nothing about intervening state changes.
This chosen later request succeeds with v2; the Sunset date is unchanged. The retirement hint is not a freeze of the resource state.
Source for this drawing: RFC 8594 · Read RFC section 4 ↗
New to this? Start hereA quick picture + helpful background
A message needs an address.
Think of a packet as a small addressed envelope. Devices pass it onward; transport protocols decide what delivery promises an application gets.
Helpful first, if these ideas are unfamiliar
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Terms in this drawing
- Representation
- The response content describing resource state at a point in time.
- Cache freshness
- Whether a saved response can be reused as fresh under its caching rules.
- max-age=60
- An illustrative 60-second freshness lifetime, not a Sunset value.
Related RFCs and changes
“Updates” changes part of an earlier RFC. “Obsoletes” replaces it. This list shows selected related documents.
A retirement date does not make today’s representation fresh until that date.
- Caching concerns reusable representations of resource state. Sunset is not concerned with state changes: the representation can change before the advertised retirement time.
- Sunset and caching are complementary. Do not substitute Sunset for Expires or Cache-Control, or infer a cache lifetime from the time remaining until retirement.
- Intermediaries such as archives and search engines can warn about possible unavailability, while still handling changing representations and uncertain availability normally.
Independent illustrative values: Sunset remains 11 November 2026, while Cache-Control: max-age=60 describes a response generated on 20 October. At an estimated age of 61 seconds the response is no longer fresh under this chosen max-age; normal cache policy applies. A separate successful request can reveal representation v2 well before November. This is not a full cache-selection or revalidation algorithm, nor a claim that retirement is guaranteed.
Read the RFC section ↗