- From: Ari Luotonen <luotonen@netscape.com>
- Date: Tue, 15 Apr 1997 18:41:08 -0700 (PDT)
- To: Jeffrey Mogul <mogul@pa.dec.com>
- Cc: http-wg@cuckoo.hpl.hp.com
> I propose adding this to the end of section 13.9: > > Note that some HTTP/1.0 cache operators have found that it is > dangerous to cache responses to requests for URLs including the > string "cgi-bin". HTTP/1.1 caches should follow this practice > for responses that do not include an explicit expiration time. > HTTP/1.1 origin servers that want to allow caching of responses > for URLs including "?" or "cgi-bin" SHOULD include an explicit > expiration time. Explicit expiration times may be specified > using Expires, or the max-age directive of Cache-Control, or > both. > > -Jeff > > P.S.: I base the first sentence in the note on the sample configuration > file distributed with a recent version of the Squid cache software. > If this is actually contrary to normal practice, someone should say so. Actually, the simple #1 rule for caching/non-caching of all time is: NEVER cache an HTTP/1.0 response that does not carry a Last-modified: header. This supercedes any heuristics based on URLs containing strings like "cgi-bin", ".cgi" or "htbin". It's also intuitive: if a response doesn't content L-M it implies that it probably didn't exist in this form before I asked for it, and probably won't exist in this form after so it's not worth caching. This rule is strictly obeyed by both CERN and Netscape Proxies. Specific proxy applications that know their data source intimately may break this rule. This assumes that the freshness of documents is guaranteed by configuration, not by the protocol. I've always strongly encouraged that both Last-modified: and Expires: be sent out from CGI's whose result is produced from data that has a specific last modification time, and will have a certain specific modification time in the future (e.g. a database that is synchronized at every midnight, but during the 24 hour period in between the response would be unchanged for the same request). Cheers, -- Ari Luotonen, Mail-Stop MV-061 Opinions my own, not Netscape's. Netscape Communications Corp. ari@netscape.com 501 East Middlefield Road http://home.netscape.com/people/ari/ Mountain View, CA 94043, USA Netscape Proxy Server Development
Received on Tuesday, 15 April 1997 18:44:29 UTC