Thx Scott & Roland. Using &amp;<@RANDOM> will indeed cause the freshly updated image to be displayed for the admin user that updated the content.

But I really want the cached items refreshed, so that other users will get the new thumbnail. I hate the idea of losing the ability to cache, but I need to think about this.

bill

On Thursday, August 4, 2005, at 01:26  PM, Scott Cadillac wrote:

Hi Bill,

Have you tried:

<img src="download.taf?_uid1=<@COLUMN "thumb_id">&random=<@RANDOM>">

Just have your server-side code ignore the "random" argument.

Works for me.

~ Scott Cadillac
~ 403-254-5002
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~ Custom Software for Business
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-----Original Message-----
From: Bill Conlon [mailto:[EMAIL PROTECTED]
Sent: Thursday, August 04, 2005 2:21 PM
To: Witango-Talk
Subject: Witango-Talk: HTTP file cache

I know a few people on this list have addressed the issue of dealing
with cached files.  Here's my scenario:

I go to an admin page, and get some info on a file stored in the db.
The page includes a thumbnail (also stored in the db), such as:

<img src="download.taf?_uid1=<@COLUMN "thumb_id">

the browser requests and caches the thumbnail image.  Response header
for this download is:

http://ccmh3.tothept.com/download.taf?_uID=165

Date: Thu, 04 Aug 2005 19:13:17 GMT
Server: Apache/2.0.54 (Unix) mod_perl/1.99_16 Perl/v5.8.5 DAV/2
PHP/4.3.10
Accept-Ranges: bytes
content-disposition: inline; filename=spiritofcaring_gray_thumb.jpg
Last-Modified: Monday, 22-Sep-2003 10:48:26 GMT
Content-Length: 5448
Content-Type: image/jpeg

I then upload a replacement file, and in the process, the application
invokes ImageMagick to generate a new thumbnail, and then
displays the
same page with updated information.  Again the thumbnail is
referenced
as

<img src="download.taf?_uid1=<@COLUMN "thumb_id">

but the previous, cached, version appears.

If I force a cache refresh, my new response header looks like:

http://ccmh3.tothept.com/download.taf?_uID=165

Date: Thu, 04 Aug 2005 19:42:50 GMT
Server: Apache/2.0.54 (Unix) mod_perl/1.99_16 Perl/v5.8.5 DAV/2
PHP/4.3.10
Accept-Ranges: bytes
content-disposition: inline;
filename=thumb_spiritofcaring_logo_gray_sm.png
Last-Modified: Thursday, 04-Aug-2005 12:42:05 GMT
Content-Length: 6681
Content-Type: image/png

The thumbnail info is generally static, and should therefore be
cacheable, but in this case I'm displaying the stale info.
Does anyone
know any tricks, or must I instead create an entirely new URI, giving
the thumbnail a new ID?

thanks.

Bill

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