From bbf5bfc9afb252d3584f1b695b1fd3c0dff9978d Mon Sep 17 00:00:00 2001 From: Mark Nottingham Date: Thu, 19 Apr 2018 17:38:00 +1000 Subject: [PATCH] talk about max-age vs expires Fixes #584 --- draft-ietf-httpbis-bcp56bis.md | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/draft-ietf-httpbis-bcp56bis.md b/draft-ietf-httpbis-bcp56bis.md index 867710257..540fd4dac 100644 --- a/draft-ietf-httpbis-bcp56bis.md +++ b/draft-ietf-httpbis-bcp56bis.md @@ -620,6 +620,11 @@ repeatedly. In general, if it is safe to reuse something, consider assigning a f cache implementations take active measures to remove content intelligently when they are out of space, so "it will fill up the cache" is not a valid concern. +The most common method for specifying freshness is the max-age response directive ({{?RFC7234}}, +Section 5.2.2.8). The Expires header ({{?RFC7234}}, Section 5.3) can also be used, but it is not +necessary to specify it; all modern cache implementations support Cache-Control, and specifying +freshness as a delta is both more convenient in most cases, and less error-prone. + Understand that stale responses (e.g., one with "Cache-Control: max-age=0") can be reused when the cache is disconnected from the origin server; this can be useful for handling network issues. See {{?RFC7234}}, Section 4.2.4, and also {{?RFC5861}} for additional controls over stale content.