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

[Germer, Carsten]

Well, sadly I didn't find the time to pursue the issue any further yet.
We're kneedeep in work to get the system up and running and caching isn't
top priority so far.
I don't even know if someone patched the AHCM yet, simply haven't looked.

But as someone suggested somewhere and you can see in
http://mail.zope.org/pipermail/zope/2003-April/135101.html it works if you
set the headers yourself.
So if you need caching _now_ and AHCM is not fixed yet, change the object
used so that it sets the headers correctly itself.

I know that this solution is ikky but I don't know when I will have time to
tackle the issue of a comfortable cache system. Though I know I will have to
solve it sometime :)

/Carsten

> -----Ursprüngliche Nachricht-----
> Von: Bjorn Stabell [mailto:bjorn at exoweb.net]
> Gesendet: Mittwoch, 10. September 2003 13:07
> An: zope-dev at zope.org
> Cc: jh at comunit.de; Carsten.germer at desy.de
> Betreff: Re: Caching prob with AHCM and headers
> 
> 
> 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
>