Re: [dcphp-dev] Caching via "304 not modified" messages

Nice tip. Handy for those cases when you don't have enough static
content to put a cache like varnish in front of your application. I'd
get rid of the error suppresion in the IF statement:

if ((isset($_SERVER['HTTP_IF_MODIFIED_SINCE']) && strtotime($_SERVER['HTTP_IF_MODIFIED_SINCE'])==$lastModified) || $etagHeader == $etagFile
) {




In a similar vain, Zend Framework does some neat static caching using
Apache rewrite rules.
http://framework.zend.com/wiki/pages/viewpage.action?pageId=8947732

On 10/23/2012 04:55 PM, Eric Maag wrote:
> Awesome, I'd never thought of using Status Code Definitions to ease server load.
>
>
> This clever bit of code checks if a page has been modified since it
> was last displayed and if it hasn't, it sends a "304 not modified"
> header and exits, otherwise the content is loads as normal. Add the
> code below to the top of each PHP page you want to apply it to. It's
> especially useful if you serve static content via php and want it to
> be cached like ordinary HTML or CSS.
>
>
> //get the last-modified-date of this very file
> $lastModified=filemtime(__FILE__);
> //get a hash of this file
> $etagFile = md5_file(__FILE__);
> //get the HTTP_IF_MODIFIED_SINCE header if set
> $ifModifiedSince=(isset($_SERVER['HTTP_IF_MODIFIED_SINCE']) ?
> $_SERVER['HTTP_IF_MODIFIED_SINCE'] : false);
> //get the HTTP_IF_NONE_MATCH header if set
> $etagHeader=(isset($_SERVER['HTTP_IF_NONE_MATCH']) ?
> trim($_SERVER['HTTP_IF_NONE_MATCH']) : false);
>
> //set last-modified header
> header("Last-Modified: ".gmdate("D, d M Y H:i:s", $lastModified)." GMT");
> //set etag-header
> header("ETag: \"$etagFile\"");
> //make sure caching is turned on
> header('Cache-Control: public');
>
> //check if page has changed If not send 304 header and exit
> if (@strtotime($_SERVER['HTTP_IF_MODIFIED_SINCE'])==$lastModified ||
> $etagHeader == $etagFile)
> {
> header("HTTP/1.1 304 Not Modified");
> exit;
> }
>
> echo "Page last modified: ".date("d.m.Y H:i:s",time());
>
>
> source:http://papermashup.com/php-clever-caching/
>

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