On 20/12/2011 7:40 p.m., Tom Tux wrote:
Hi
I have found the following web-based tool to calculate the objects freshness:
http://web.forret.com/tools/squid.asp
If it's useful for others too, can a site-admin publish this url on
"squid-cache.org" (perhaps 'Related Software')?
Thanks and regards,
Tom
Nice tool. Although if you use it I recommend also using the redbot.org
tool to see problems with other details which affect caching service.
* it displays what it calls "header contents" dates in a format which
is invalid for HTTP.
* it omits several of the age limit directives Squid considers for the
algorithm (max_stale, and refresh_pattern max-stale=N)
* it omits about half of the cache-control directives which Squid uses
to adjust the algorithm (max-stale, stale-if-error,
stale-while-revalidate, must-revalidate, no-cache)
* it does not permit HTTP/1.1 server cache-control header contents to
be entered for consideration, this may drastically alter the algorithm
output
* it crashes the script if you put some very common invalid header
values into the input fields.
* it assumes ETag: and Vary: are identical on the client request, but
does not state that anywhere for the script user to be aware of the
relationship.
It may have worked well for Squid-2.5 and early 2.6/3.0 responses but
newer Squid as you can see from the above, have quite a few more
protocol details and config settings involved with the calculation.
Side Note:
we are working upstream on JavaScript extensions to the cache manager
reports. If anyone feels interest towards creating a JS script which can
take cached object headers and config details and produce a little
service-state report like that tools output please contact kinkie via
the squid-dev mailing list about it.
Amos
