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

[Germer, Carsten]

Thanks Bjorn, now I remember the last-modified issue.
As I remember it, someone said that the line is commented out for a reason
not known... that's why I didn't change it :)
/Carsten


 -Ursprüngliche Nachricht-
 Von: Bjorn Stabell [mailto:[EMAIL PROTECTED]
 Gesendet: Freitag, 12. September 2003 12:14
 An: [EMAIL PROTECTED]
 Cc: Janko Hauser; [EMAIL PROTECTED]; [EMAIL PROTECTED]; 
 Germer, Carsten
 Betreff: [Summary] Caching prob with AHCM and headers
 
 
 Just for the record to help others in the same situation...
 
 PROBLEM
 Apache (1.3.28 and 2.0.47) will not cache content with just an Expires
 header, but it will correctly cache content with a 
 Last-Modified header.
 This problem has been reported before in 1999 by James Cooper, but the
 bug request seems to have been forgotten/ left behind.
 
 It makes sense for dynamic content to produce Expires headers, not
 Last-Modified headers, so this is a problem.
 
 Looking at the code for Zope, it seems that the standard HTTP
 accelerator product used to produce a Last-Modified header, but no
 longer does so, thus making it useless with the current versions of
 Apache.
 
 The problem has been re-reported to the Apache group with patches:
 http://nagoya.apache.org/bugzilla/show_bug.cgi?id=23129 (for Apache
 1.3.28)
 http://nagoya.apache.org/bugzilla/show_bug.cgi?id=23130 (for Apache
 2.0.47)
 
 
 WORK-AROUNDS
 1) Produce a Last-Modified header yourself by using
 2) Patch Zope's standard HTTP accelerator product so that it 
 produces a
 Last-Modified header (the line is commented out now)
 
 SOLUTIONS
 3) Patch Apache (see bug report links above for patches)
 4) Wait until the problem is hopefully fixed in Apache
 
 
 Bye,
 -- 
 Bjorn Stabell [EMAIL PROTECTED]
 Tel +86 (10) 65918490
 

___
Zope-Dev maillist  -  [EMAIL PROTECTED]
http://mail.zope.org/mailman/listinfo/zope-dev
**  No cross posts or HTML encoding!  **
(Related lists -
 http://mail.zope.org/mailman/listinfo/zope-announce
 http://mail.zope.org/mailman/listinfo/zope )

[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:[EMAIL PROTECTED]
 Gesendet: Mittwoch, 10. September 2003 13:07
 An: [EMAIL PROTECTED]
 Cc: [EMAIL PROTECTED]; [EMAIL PROTECTED]
 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
 

___
Zope-Dev maillist  -  [EMAIL PROTECTED]
http://mail.zope.org/mailman/listinfo/zope-dev
**  No cross posts or HTML encoding!  **
(Related lists -
 http://mail.zope.org/mailman/listinfo/zope-announce
 http://mail.zope.org/mailman/listinfo/zope )