time.php source code

The following is the source code for time.php. To make it a valid PHP / XHTML file, remove the CDATA tag from the top and the end CDATA tag from the bottom, then re-add the begin and end CDATA tags that were originally in the file; the removed tags are marked with the word "CDATA" amongst other markings.


<![CDATA[


<?php 
/* 
This web page / app displays client and server time in various formats.  
It uses JavaScript to get client time and compares server time to client time down to the millisecond.  

Part of the purpose is to show that the server is alive.  

*********
written by Kwynn Buess
As of April 22, 2011, this page runs on  http://kwynn.com/t/0/11/time/time.php
version timestamp 4:57am

There's nothing original here worth copyrighting.  Do what you want with the code.  If the code helps you 
or inspires you to write your own, give me credit by name and by web site (if my site is still 
up).
**********

As you probably know, http://php.net is very helpful for looking up functions.  

I make one hard-coded assumption, that the time zone is a USA time zone.  I couldn't think of any easy way 
around that.  It's listed as "BIG ASSUMPTION!!!" below.
*/

/* 

**************************************
The following header lines make sure that the page isn't held in the cache--each time the page is requested, 
it gives the page time as the current time (as opposed to the file time).  These lines must go before anything 
else because they emit an HTTP "header" before page content.  


In most cases, web sites seem to give their "Last-Modified" in GMT.  I'm not sure if it's required, but I'll 
go with it.  
*/

// I need microseconds (useconds) only because I use them to compare to server time further below.  
// useconds are not needed for the "header()"

	$utime = microtime(true); // a floating point
	$usecondsOnly = sprintf("%06d",($utime - floor($utime)) * 1000000);

	// The following is relatively complex to preserve the useconds.  
	$serverDTimeO = new DateTime( date('Y-m-d H:i:s.' . $usecondsOnly, $utime) ); // server Date Time Object
	// previous 3 lines credited at bottom 

	$gmt = new DateTimeZone('Etc/GMT+0');
	$serverDTimeO->setTimeZone($gmt);	
	header("Last-Modified: " . $serverDTimeO->format("D, d M Y H:i:s") . " GMT");

	// reset timezone where I want it
	$et = new DateTimeZone('America/New_York'); // et = Eastern Time
	$serverDTimeO->setTimeZone($et);

?> 

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en-US" lang="en-US">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />

<title>Time / Hello World (I'm alive!)</title>

<script type='text/javascript'>

// The following line is needed for XHTML compliance--to "hide" the JavaScript code
// 

***** Add a begin CDATA tag on this line.  The existing one had to be removed ***



 
/**************************/
// Server time ("$serverDTimeO") has been captured above.  In the function below, take client time, format appropriately, and compare client and server time.  

//  output looks like this:
/*
client 	1303458940.685
server 	1303458939.579385
diff 	         0.106  
*/

function displayClientServerTimeDiff()
{
	var dateO = new Date(); // JavaScript date object
	var clientTimeInMSSinceEpoch = dateO.getTime(); // time in milliseconds since UNIX Epoch 
							// such as 1303454690212

	// display client time in seconds to 3 decimal places, such as 1303454690.212
	// then zero fill such as 130.300 or 130.450 rather than 130.3 or 130.45
	var clientTimeInS = toSecAndZeroFill3DecimalPlaces(clientTimeInMSSinceEpoch); 
	document.getElementById('clientTimeDOMID').innerHTML = clientTimeInS;
					
	
	// express server time in the form "epoch seconds.microseconds" such as 1303454690.212945
	// then convert PHP to JavaScript
	var serverTime	= <?php echo $serverDTimeO->format('U') . "." . $serverDTimeO->format('u'); ?>;

	// without the Number cast, might confuse for string
	var diff = Number(clientTimeInS) - Number(serverTime); // such as 0.140130s
	var diffrndms = Math.round(diff * 1000); // diff rounded in ms, such as 140
	var diffrnd = diffrndms / 1000; // diff rounded, such as 0.14 
	var zeroF3 =  zeroFill3(diffrnd); // 0.140

	// nbsp spaces needed to align properly
	document.getElementById('diff')  .innerHTML = zeroF3 + "   "; 
	document.getElementById('diffms').innerHTML = diffrndms; // 140

	// if diff is above so many seconds, highlight the output in colors
	var red = 5;
	var yel = 2;

	if 	(diff > red || diff < -red) document.getElementById('diffTag').style.background = 'red';
	else if (diff > yel || diff < -yel) document.getElementById('diffTag').style.background = 'yellow';

} // end function displayClientServerTimeDiff()


/***********************************/
// input is 1303457815340ms
function toSecAndZeroFill3DecimalPlaces(msIN)
{
	// because round only results in integers, must dance a bit
	var modulus = msIN % 1000; // 34 (0 is lost)
	var whole = Math.round(msIN / 1000); // 1303457815
	var ret = whole + (modulus / 1000); // 1303457815.34

	return zeroFill3(ret);
}


/*************************/
// turns 3 into 3.000
// turns 0.3 into 0.300
// turns 0.32 into 0.320

function zeroFill3(ins) // ins = incoming string, or it will be a string in a moment
{

	ins = ins.toString();
	var decimalPos = ins.search(/\./);
	var len        = ins.length;

	if (decimalPos < 0) ins += ".000";
	else if (len - decimalPos == 3) ins += "0" ;
	else if (len - decimalPos == 2) ins += "00";

	return ins;
}

// the following ends the CDATA section
// 

***** Add an end CDATA tag on this line.  The existing one had to be removed ***


</script>



</head>

<body>
<!-- note that I'm tying to keep everything on one screen without scrolling -->

<?php

?>

<p  style='font-size: 120%; text-align: right; margin-right: 5%'>
<?php echo $serverDTimeO->format('D M j, g:i A'); 
		// ie, Fri Apr 22, 4:00 AM, meant to match the Gnome Desktop environment default clock
?>
</p>

<!-- *************************** -->
<!-- section populated by JS functions above.  Monospace to align properly -->
<div style='font-family: monospace; font-size: 130%; float: left; margin-bottom: 1em'>

<!-- output like this:
UNIX Epoch 
client 	1303459220.407
server 	1303459220.211666
diff 	         0.195
-->

<table>
<caption style='text-align: left; margin-bottom: 0.5em'>UNIX Epoch</caption>
<tr>
	<td>client</td><td id='clientTimeDOMID'></td>

	<!-- time in ms in large print.  Fiddled with this formatting quite a bit 
	     this text is actually offset from the main table -->	
	<td rowspan='3' style='vertical-align: bottom; margin-bottom: 0; padding-bottom: 0'>
	<span id='diffms' style='font-size: 200%; font-family: sans-serif; margin-left: 1em'></span>ms
	</td>
</tr>

<tr>
	<?php
	$stue   = $serverDTimeO->format('U'); // server time in seconds
	$stuems = $serverDTimeO->format('u'); // server time, microseconds only
	?>
	<td>server</td>	<td id='serverTimeUE'><?php echo $stue . "." . $stuems ?></td>
</tr>

<tr id='diffTag'>
	<td>diff</td><td id='diff' style='text-align: right'></td>
</tr>
</table>
</div> <!-- end diff / table section -->

<!-- CSS "float"ing -->
<p style='text-align: right; margin-right: 5%; margin-top: 5%'>
<?php 
echo "24 hour time = ";
$tfh = $serverDTimeO->format('H:i:s'); // tfh = 24 hour, ie 04:00:20
?>
<span style='font-size: 110%'><?php echo $tfh; ?></span>
</p>


<!-- ********** timezone info ************* -->

<div style='clear: both; margin-top: 2em'>
</div>

<p>
<?php 

$dstb = $serverDTimeO->format('I'); // daylight savings time boolean
if ($dstb) 	$dsts = "yes";  // dst string
else		$dsts = "no";

echo "timezone info = GMT ";

// such as GMT -0400 O = -0400
echo $serverDTimeO->format('O');
echo ", ";
echo "USA ";  // BIG ASSUMPTION!!!  comment out if need be

// T = time zone abbreviation, such as (USA) EDT
echo $serverDTimeO->format('T');
echo "; daylight saving = " . $dsts; // yes or no
echo "<br/>\n";
echo "timezone of continent/reference city = " . $serverDTimeO->format('e'); // such as America/New_York
?>
</p>
<!-- ******* END timezone ******* -->

<!-- ****** misc stuff ***** -->
<p style='float: left; margin-top: 0.2em'>
<?php echo number_format($serverDTimeO->format('U')); ?> (server UNIX Epoch with commas)
</p>

<p style='float: right; margin-right: 5%; margin-top: 0.2em'>
<?php echo "year = " . $serverDTimeO->format('Y'); ?>
</p>

<p style='clear: both'>
	<a href='./time_explained.html'>explanation</a> of this page's purpose
	<span style='margin-left: 4em'><a href='time_source.php'>this page's source code</a></span>
	<span style='margin-left: 4em'><a href='../../../../'>home</a></span>
</p>

<p style='margin-top: 1.5em; float: left'>
    <a href="http://validator.w3.org/check?uri=referer"><img
        src="../../../../valid-xhtml10.png"
        alt="Valid XHTML 1.0 Strict" height="31" width="88" /></a>
</p>

<p style='font-size: 200%; text-align: right; margin-right: 1%'>
<?php echo $serverDTimeO->format('g:iA'); 
		// such as 4:17AM in large print, meant to match the Windows clock
?>
</p>


<script type='text/javascript'>

	displayClientServerTimeDiff();

</script>

</body>
</html>

<!--
The first few lines of the "Last Modified" header code at top is from 
http://us3.php.net/manual/en/function.date.php
a comment by Edward Rudd, 05-Oct-2009 01:13
-->



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