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From "David Wortham" <djwort...@gmail.com>
Subject Re: Questions on modules to provide cache functions for Apache
Date Tue, 06 Mar 2007 23:43:14 GMT
Erica,
   My only comments: either
(1) the request parameters are killing mod_cache's desire to cache the file
or
(2) something is different in the headers between your JavaScript and PHP
responses.

I would:
(1) Try requesting /gethint.php without any GET/POST parameters (your app
should respond with correctly formatted XML [probably returning an error
code]).  Is this file cached (with/without the force-caching directive)?
(2) Compare the javascript and xml response headers and compare any
differences.  I would think forcing mod_cache to ignore all headers would
make this trivial... but this may reveal something which may be missing.
(3) Clear your cache directory and see if your XML response creates a file,
then check if your javascript file creates a cache file (assuming you are
still using mod_file_cache)

Regards,
Dave


On 3/6/07, Erica Zhang <ericazhj@cs.ubc.ca> wrote:
>
> Yes. I changed the PHP script. Now I change them back and also set
> CacheIgnoreCacheControl On. And still could not work. For other
> questions, please see the my answers below. Thanks.
>
> David Wortham wrote:
>
> > Erica,
> >   My observations of your headers:
> > (1) The "Last-Modified" line contains the current timestamp (as
> expected)
>
> After I set CacheIgnoreCacheControl On, it does not matter. Right ?
> Although I move the headers to the top code, it still could not work.
>
> > (2) Your original question showed that you inserted an "Expires:"
> header,
> > but it doesn't show in your response.  Did you change your PHP script
> > code
> > since you asked the original question this morning?
>
> Yes. It is my fault.
>
> > (3) Are you returning XML or HTML?  My experience with
> XMLHttpResponse(s)
> > required changing the content-type to "text/xml" (not really the issue
> at
> > hand)
> >
> Does it matter ?
>
> > When you said that you got mod_cache to cache a JavaScript file, was
> > it in
> > the same directory (and covered by the same mod_cache directives)?
>
> Yes, both javascript file and the php file are under htdocs directory.
>
> >
> > Did you try using the
> > CacheIgnoreCacheControl On
> > directive?  Did it force the file to cache?
>
> I tried. But it could not work.
>
> >
> > Regards,
> > Dave
> >
> >
> > On 3/6/07, Erica Zhang <ericazhj@cs.ubc.ca> wrote:
> >
> >>
> >> I use live http headers to catch the headers. I listed them below. Well
> >> I found that php file has not been given the http headers. So is this
> >> the problem for not caching the response produced by it ? Then how can
> I
> >> handle this problem ? Also, is there some mod_cache log that I could
> >> refer ? Thanks.
> >>
> >> http://128.189.246.64/gethint.php?q=Eric&sid=0.11837499670287688
> >>
> >> GET /gethint.php?q=Eric&sid=0.11837499670287688 HTTP/1.1
> >> Host: 128.189.246.64
> >> User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.8.1.2)
> >> Gecko/20070219 Firefox/2.0.0.2
> >> Accept:
> >> text/xml,application/xml,application/xhtml+xml,text/html;q=0.9
> >> ,text/plain;q=0.8,image/png,*/*;q=0.5
> >> Accept-Language: en-us,en;q=0.5
> >> Accept-Encoding: gzip,deflate
> >> Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.7
> >> Keep-Alive: 300
> >> Connection: keep-alive
> >> Referer: http://128.189.246.64/
> >>
> >> HTTP/1.x 200 OK
> >> Date: Tue, 06 Mar 2007 22:35:34 GMT
> >> Server: Apache/2.0.59 (Win32)
> >> X-Powered-By: PHP/4.4.4
> >> Cache-Control: public
> >> Last-Modified: Tue, 06 Mar 2007 22:35:34 GMT
> >> Keep-Alive: timeout=15, max=10000
> >> Connection: Keep-Alive
> >> Transfer-Encoding: chunked
> >> Content-Type: text/html
> >>
> >>
> >> Erica Zhang wrote:
> >>
> >> > Well, even I use the blinding-cache. It still could not work. Thanks,
> >> >
> >> > Erica
> >> >
> >> > David Wortham wrote:
> >> >
> >> >> Erica,
> >> >>   I'm not sure why mod_cache should not be able to work (assuming
> >> your
> >> >> module and pages are configured correctly).
> >> >>
> >> >>   IIRC, JavaScript is used on the presentation request (with the
> >> >> webpage),
> >> >> whereas the XMLHttpRequest response is a PHP-generated XML document.
> >> >> Perhaps your extension ('.php" maybe?) or the mime/content-type
> >> >> ("text/xml")
> >> >> is what is causing mod_cache to skip the file?
> >> >>
> >> >>   Also, from what I can gather, using mod_cache with mod_proxy (as
a
> >> >> caching proxy) can alter the effects of mod_cache slightly.  You may
> >> >> want to
> >> >> read up on that.
> >> >>
> >> >> Try using the following directive with mod_cache:
> >> >> CacheIgnoreNoLastMod On
> >> >>
> >> >> see:
> >> >>
> >>
> http://webauth.stanford.edu/manual/mod/mod_cache.html#CacheIgnoreNoLastMod
> >>
> >> >>
> >> >>
> >> >> This apparently forces blind-caching which Joe suggests is bad (I
> >> >> don't know
> >> >> anything about it).  Short of that, you just need to read the
> >> mod_cache
> >> >> manual and make sure your XML response contains the necessary
> headers
> >> >> to get
> >> >> mod_cache to work correctly.
> >> >>
> >> >> Regards,
> >> >> Dave
> >> >>
> >> >>
> >> >>
> >> >> On 3/6/07, Erica Zhang <ericazhj@cs.ubc.ca> wrote:
> >> >>
> >> >>>
> >> >>> No, still not work. Infact, mod_cache could work, because it could
> >> >>> cache
> >> >>> the javascript. But it could not work for dynamic HTTP responses
> >> >>> responding to XMLHttpRequests in Ajax technology. So I suspect
> >> >>> mod_cache
> >> >>> could not support this function. And I need provide such function
> by
> >> >>> myself. I prefer to do it in Apache, a comparatively general way
> >> >>> instead
> >> >>> of application itself.
> >> >>>
> >> >>>
> >> >>> Erica
> >> >>>
> >> >>> Joachim Zobel wrote:
> >> >>>
> >> >>> >Am Montag, den 05.03.2007, 22:53 -0800 schrieb Erica Zhang:
> >> >>> >
> >> >>> >
> >> >>> >>header("Cache-Control: public"); // HTTP/1.1
> >> >>> >>header("Expires: " .gmdate ("D, d M Y H:i:s", time() +
60 * 10).
> "
> >> >>> GMT");
> >> >>> >>header( "Last-Modified: " .gmdate( 'D, d M Y H:i:s' ).
" GMT" );
> >> >>> >>echo $response;
> >> >>> >>
> >> >>> >>
> >> >>> >
> >> >>> >I am not shure about mod_caches behaviour, but omitting
> >> >>> last-modified is
> >> >>> >worth a try.
> >> >>> >
> >> >>> >Sincerely,
> >> >>> >Joachim
> >> >>> >
> >> >>> >
> >> >>> >
> >> >>>
> >> >>>
> >> >>
> >>
> >>
> >
>
>

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