HTTP Compression

Some time ago I found interesting class HTTP_Compress. Just add this code to _setHeaders():

<?php
if($conf['site']['compression']) {
     require_once('HTTP/Compress.php');
     HTTP_Compress::start();
}
?>

and this code at the end of _displayPage():

<?php
if($conf['site']['compression']) {
     HTTP_Compress::output();
}
?>

I found also that internet explorer 5 often crashed (very very often) on sites with compression on. Here is a little workaround: in _setHeaders():

<?php
if($conf['site']['compression']) {
     require_once('HTTP/Compress.php');
     require_once('Net/Detect.php');
     $bw = Net_UserAgent_Detect::singleton();
     if( !$bw->isBrowser('ie5') ) {
         $this->compress = true;
         HTTP_Compress::start();
     }
}
?>

and to _displayPage():

<?php
if(!empty($this->compress] {
     HTTP_Compress::output();
}
?>

best regards, Radek

<?php
''
'' +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~+
'' | PHP Version 4                                                        |
'' +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~+
'' | Copyright (c) 1997-2002 The PHP Group                                |
'' +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~+
'' | This source file is subject to version 2.02 of the PHP license,      |
'' | that is bundled with this package in the file LICENSE, and is        |
'' | available at through the world-wide-web at                           |
'' | http://www.php.net/license/2_02.txt.                                 |
'' | If you did not receive a copy of the PHP license and are unable to   |
'' | obtain it through the world-wide-web, please send a note to          |
'' | license@php.net so we can mail you a copy immediately.               |
'' +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~+
'' | Authors: Mark Nottingham <mnot@pobox.com>                            |
'' |          Chuck Hagenbuch <chuck@horde.org>                           |
'' +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~+
''
'' $Id: Compress.php,v 1.1 2004/01/25 10:35:32 chief Exp $
''

/'''
 * HTTP_Compress:: provides a wrapper around php's output buffering
 * mechanisms and also does compression, generates headers - ETag,
 * Content-Length, etc. - which may be beneficial to bandwidth
 * usage and performance.
 *
 * @author Mark Nottingham <mnot@pobox.com>
 * @author Chuck Hagenbuch <chuck@horde.org>
 * @version $Revision: 1.1 $
 * @package HTTP
 */
class HTTP_Compress {
    
    /'''
     * Start the output buffer, and make sure that implicit flush is
     * off so that data is always buffered.
     * @access public
     */
    function start()
    {
        ob_start();
        ob_implicit_flush(0);
    }
    
    /'''
     * Output the contents of the output buffer, compressed if
     * desired, along with any relevant headers.
     *
     * @param boolean $compress (optional) Use gzip compression, if the browser supports it.
     * @param boolean $use_etag Generate an ETag, and don't send the body if the browser has the same object cached.
     * @param boolean $send_body Send the body of the request? Might be false for HEAD requests.
     * @access public
     */
    function output($compress = true, $use_etag = true, $send_body = true)
    {
        $min_gz_size = 1024;
        $page = ob_get_contents();
        $length = strlen($page);
        ob_end_clean();
        
        if ($compress && extension_loaded('zlib') && (strlen($page) > $min_gz_size) && isset($GLOBALS['HTTP_SERVER_VARS']['HTTP_ACCEPT_ENCODING']] {
            $ae = explode(',', str_replace(' ', '', $GLOBALS['HTTP_SERVER_VARS']['HTTP_ACCEPT_ENCODING']];
            $enc = false;
            if (in_array('gzip', $ae] {
                $enc = 'gzip';
            } else if (in_array('x-gzip', $ae] {
                $enc = 'x-gzip';
            }
            
            if ($enc) {
                $page = gzencode($page);
                $length = strlen($page);
                header('Content-Encoding: ' . $enc);
                header('Vary: Accept-Encoding');
            } else {
                $compress = false;
            }
        } else {
            $compress = false;
        }
        
        if ($use_etag) {
            $etag = '"' . md5($page) . '"';
            header('ETag: ' . $etag);
            if (isset($GLOBALS['HTTP_SERVER_VARS']['HTTP_IF_NONE_MATCH']] {
                $inm = explode(',', $GLOBALS['HTTP_SERVER_VARS']['HTTP_IF_NONE_MATCH']);
                foreach ($inm as $i) {
                    if (trim($i) == $etag) {
                        header('HTTP/1.0 304 Not Modified');
                        $send_body = false;
                        break;
                    }
                }
            }
        }
        
        if ($send_body) {
            header('Content-Length: ' . $length);
            echo $page;
        }
    }
    
}
?>