Hidden iFrame Technique - A.K.A Comet

gookymedia · November 30, 2010

Hi

I am using Comet programming and the hidden iframe (the only real way to push data with php)

I have this working perfectly on one server but another it just shows a constant blank screen. I have both servers in the php.ini with output buffering to On, no set size but also the script itself outputs over 250 characters to compensate for some browsers buffers.

I just don't understand why it works on one server but not another! Just for note, it only does this when i use the sleep() function...but like I say this works on one of my servers.

Here is the example program to test the functionality. On this site is works : www.gookymedia.com/comet but here, the exact same code does not : www.jointsocial.com/comet

This is one of the most baffling things I have come across in php programming so far, and believe me I have written some complex applications over the years! I could do with someone to point out whats going wrong (if anyone has ever done this before)

CODE FOR index.php

<?php

ob_implicit_flush();
?>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN" "http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
    <head>
    	<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
        <title>CD Store</title>
        <script type="text/javascript">
        	function updateTest(count){
			document.getElementById('test').innerHTML = "Number " + count;
		}
        </script>
    </head>
    
    <body>
        
        <div style="width: 200px; height: 50px; color: red;" id="test"></div>
        <iframe name="hidden" id="hidden" height="0" width="100%"></iframe>
        
        <script type="text/javascript">
            
            document.getElementById ( 'hidden').src = 'test.php';
            
        </script>
        
    </body>
    
</html>

CODE FOR test.php

<?php
set_time_limit(0);
ob_implicit_flush();

header("Cache-Control: no-cache, must-revalidate");
header("Expires: Mon, 26 Jul 1997 05:00:00 GMT");
flush();


$count = 1;

do {} while ( updateCount() > 0 );

function updateCount() {
    
    global $count;
  
    echo '                                                                                                    ';
    echo '                                                                                                    ';
    echo '<script type="text/javascript">parent.updateTest ( "' . $count . '" );</script>';
    
    flush();
    sleep(1);

    
    $count++;
    
    return $count;
}

?>

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Hidden iFrame Technique - A.K.A Comet

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