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POBrowser Cache Control, Dynamic Content
 

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    <p><strong>Problem:</strong> I can't seem to get FireFox to cache images sent from a dynamic server</p> <p><strong>Setup:</strong> Static Apache Server with reverse proxy to a dynamic server (mod_perl2) at backend.</p> <p>Here is the request URL for the server. It is sent to the the dynamic server, where the cookie is used to validate access to the image:</p> <p><strong>Request Headers</strong></p> <pre><code>Host: &lt;OBSCURED&gt; User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.9.0.15) Gecko/2009102815 Ubuntu/9.04 (jaunty) Firefox/3.0.15 Accept: image/png,image/*;q=0.8,*/*;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: &lt;OBSCURED&gt; Cookie: pz_cred=4KCNr0RM15%2FJCOt%2BEa6%2BL62z%2Fxvbp2xNQHY5pJw5d6Q Pragma: no-cache Cache-Control: no-cache </code></pre> <p>The dynamic server streams the image back to the server, and provides the following response:</p> <p><strong>Response Headers</strong></p> <pre><code>Date: Tue, 24 Nov 2009 04:28:07 GMT Server: Apache/2.2.11 (Ubuntu) mod_apreq2-20051231/2.6.0 mod_perl/2.0.4 Perl/v5.10.0 Cache-Control: public, max-age=31536000 Content-Length: 25496 Content-Type: image/jpeg Via: 1.1 127.0.1.1:8081 Keep-Alive: timeout=15, max=75 Connection: Keep-Alive </code></pre> <p>So far, so good (me thinks). However, <strong>on reload of the page</strong>, the image does not appear cached, and a request is again sent:</p> <p><strong>Request Headers</strong></p> <pre><code>Host: &lt;OBSCURED&gt; User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.9.0.15) Gecko/2009102815 Ubuntu/9.04 (jaunty) Firefox/3.0.15 Accept: image/png,image/*;q=0.8,*/*;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: &lt;OBSCURED&gt; Cookie: pz_cred=4KCNr0RM15%2FJCOt%2BEa6%2BL62z%2Fxvbp2xNQHY5pJw5d6Q Cache-Control: max-age=0 </code></pre> <p>It doesn't seem that request should happen as the browser should have cached the image. As it is, a 200 response is received, same as the first, and the image appears to be re-fetched (although the browser does appear to be using the cached images).</p> <p>The problem appears to be hinted at by the Cache-Control: max-age=0 in the reload request header, above.</p> <p>Does anyone know why this is happening? Perhaps it is the <strong>Via</strong> header in the response that is causing the problem?</p>
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