[Zope-dev] Re: Caching prob with AHCM and headers

[Bjorn Stabell]

Accelerated HTTP Caching Manager doesn't work out-of-the-box as this
thread reported, but the thread had no conclusion:

http://mail.zope.org/pipermail/zope/2003-April/134800.html
http://mail.zope.org/pipermail/zope/2003-April/135059.html
http://mail.zope.org/pipermail/zope/2003-April/135101.html

I'm running into the same problem now, also with Apache as the caching
reverse proxy, so I was wondering if there was any progress?  Here are
some of my thoughts;

It seems reasonable that without a Last-Modified or Etag header in the
response, that a client (and surrogate/ http accelerator) will not have
any validators (e.g., If-Modified-Since or If-Match corresponding to
last modified and etag headers, respectively) in the request headers.

It's probably right that dynamic code doesn't return a Last-Modified
header; instead, the RFC includes an Etag header, which is hash of the
content, which is much easier to use for dynamic code.  The Etag header
returned by Zope, however, looks very suspicous; it is empty.  This
could perhaps be fooling the caching machinery?

Perhaps the Etag header should just always be a hash of the content?
(Another system worth looking at: http://www.jpcache.com/)

Bye,
-- 
Bjorn