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From Erica Zhang <erica...@cs.ubc.ca>
Subject Re: Questions on modules to provide cache functions for Apache
Date Wed, 07 Mar 2007 00:13:20 GMT
David,

1) I tried /gethint.php without any GET/POST parameters. I got nothing 
and it could not be cached even with force-caching directive. I do the 
same thing for clienthint.js. It could work and display the source code 
and could be cached.

2), The first part is the responses for clienthint.js:

HTTP/1.x 200 OK
Date: Wed, 07 Mar 2007 00:05:08 GMT
Server: Apache/2.0.59 (Win32)
Last-Modified: Tue, 06 Mar 2007 01:57:50 GMT
*Etag: "88a26cc0-3ed-66b16380"*
*Accept-Ranges: bytes
Content-Length: 1005*
Keep-Alive: timeout=15, max=9999
Connection: Keep-Alive
*Content-Type: application/x-javascript*

The second part is the response for gethint.php:

HTTP/1.x 200 OK
Date: Wed, 07 Mar 2007 00:06:12 GMT
Server: Apache/2.0.59 (Win32)
X-Powered-By: PHP/4.4.4
Cache-Control: public
*Expires: Wed, 07 Mar 2007 00:16:12 GMT*
Last-Modified: Wed, 07 Mar 2007 00:06:12 GMT
Keep-Alive: timeout=15, max=10000
Connection: Keep-Alive
*Transfer-Encoding: chunked
Content-Type: text/html*

I make the different header parts in bold.

3) Do you think I need to use mod_file_cache ? I do not use it.

Regards,

Erica


David Wortham wrote:

> 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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