httpd-dev mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From Graham Leggett <>
Subject Re: mod_proxy Cache-Control: no-cache=<directive> support Apache1.3
Date Sat, 09 Mar 2002 05:40:54 GMT
Igor Sysoev wrote:

> Do you mean that Squid returns cached gzipped content to client
> that does not send 'Accept-Encoding' ? mod_proxy 1.3.23 does the same.
> Would it be changed in 1.3.24 ?

Looking into this further, proxy uses the HTTP/1.1 Vary mechanism for
determining whether a negoitated response is cacheable or not. HTTP/1.0
requests are not checked for negotiated responses. This is in line with
the behaviour of mod_negotiation, which adds Pragma: no-cache to
negotiated responses on HTTP/1.0 requests. I assume other webservers
have similar behaviour, which is why this hasn't been raised as a
problem before.

In the v1.3 mod_proxy, if a cached variant turns out not to mach the
Vary mechanism, that cached variant is deleted and a new variant is
requested. This ensures that the client is not sent the wrong variant.

In the v2.0 mod_cache, the capability exists to cache multiple variants
of the same URL simultaneously. As a result, should a cached variant fit
the client's pushlished capabilities, then that variant will be
returned, otherwise a new variant will be requested from the remote
server, possibly adding an additional variant to the cache. As mod_cache
has built in negotiation capabilities, this should in theory work with
both HTTP/1.0 and HTTP/1.1 requests.

-----------------------------------------		"There's a moon
					over Bourbon Street
View raw message