Getting information The most important part is getting information from your visitor. Thankfully, this is extremely easy to do in PHP (or any other scripting language for that matter). PHP has a special global variable called $_SERVER which contains several environment variables, including information about your visitor. To get all information you want, simply use following code:

 // Getting information $ipaddress = $_SERVER['REMOTE_ADDR']; $page = "http://{$_SERVER['HTTP_HOST']}{$_SERVER['PHP_SELF']}";  $page .= iif(!empty($_SERVER['QUERY_STRING']), "?{$_SERVER['QUERY_STRING']}", ""); $referrer = $_SERVER['HTTP_REFERER']; $datetime = mktime(); $useragent = $_SERVER['HTTP_USER_AGENT']; $remotehost = @getHostByAddr($ipaddress); 

Note: I used a function in above example called iif(). You can get this function at http://www.phpit.net/code/iif-function.

Logging information Now that you have all information you need, it must be written to a log file so you can later look at it, and create useful graphs and charts. To do this you need a few simple PHP function, like fopen (http://www.php.net/fopen) and fwrite (http://www.php.net/fwrite).

The below code will first create a complete line out of all information. Then it will open log file in "Append" mode, and if it doesn't exist yet, create it.

If no errors have occurred, it will write new logline to log file, at bottom, and finally close log file again.

 // Create log line $logline = $ipaddress . '|' . $referrer . '|' . $datetime . '|' . $useragent . '|' . $remotehost . '|' . $page . " ";
// Write to log file: $logfile = '/some/path/to/your/logfile.txt';
// Open log file in "Append" mode if (!$handle = fopen($logfile, 'a+')) { die("Failed to open log file"); }
// Write $logline to our logfile. if (fwrite($handle, $logline) === FALSE) { die("Failed to write to log file"); }   fclose($handle); 

 include ('log.php'); 

The internet wasn't made for this. The web browser closes connection with web server as soon as it has received all data. This means that after this no more data can be exchanged. What if you want to do an update though? If you're building a PHP application (e.g. a high-quality content management system), then it'd be ideal if it worked almost like a native Windows/Linux application.

But that requires real-time updates. Something that isn't possible, or so you would think. A good example of an application that works in (almost) real-time is Google's GMail. Everything is JavaScript powered, and it's very powerful and dynamic. In fact, this is one of biggest selling-points of GMail. What if you could have this in your own PHP websites as well? Guess what, I'm going to show you in this article.

How does it work? If you want to execute a PHP script, you need to reload a page, submit a form, or something similar. Basically, a new connection to server needs to be opened, and this means that browser goes to a new page, losing previous page. For a long while now, web developers have been using tricks to get around this, like using a 1x1 iframe, where a new PHP page is loaded, but this is far from ideal.

Now, there is a new way of executing a PHP script without having to reload page. The basis behind this new way is a JavaScript component called XML HTTP Request Object. See http://jibbering.com/2002/4/httprequest.html for more information about component. It is supported in all major browsers (Internet Explorer 5.5+, Safari, Mozilla/Firefox and Opera 7.6+).

With this object and some custom JavaScript functions, you can create some rather impressive PHP applications. Let's look at a first example, which dynamically updates date/time.

Example 1 First, copy code below and save it in a file called 'script.js':

 var xmlhttp=false; /*@cc_on @*/ /*@if (@_jscript_version >= 5) // JScript gives us Conditional compilation, we can cope with old IE versions. // and security blocked creation of objects.  try {  xmlhttp = new ActiveXObject("Msxml2.XMLHTTP");  } catch (e) {  try {  xmlhttp = new ActiveXObject("Microsoft.XMLHTTP");  } catch (E) {  xmlhttp = false;  }  } @end @*/ if (!xmlhttp && typeof XMLHttpRequest!='undefined') {  xmlhttp = new XMLHttpRequest(); }
function loadFragmentInToElement(fragment_url, element_id) {  var element = document.getElementById(element_id);  element.innerHTML = '<em>Loading ...</em>';  xmlhttp.open("GET", fragment_url);  xmlhttp.onreadystatechange = function() {  if (xmlhttp.readyState == 4 && xmlhttp.status == 200) {  element.innerHTML = xmlhttp.responseText;  }  }  xmlhttp.send(null); } 

 <?php echo date("l dS of F Y h:i:s A"); ?>