The front controller is a simple to understand design pattern where you have a main controller that handles every request for a website. It is a commonly used design pattern for many MVC based web applications.

To use the front controller pattern, you need to have a single part of your website that is fully responsible for handling all incoming requests to your site/application. It will often (but not always) work with a routing and templating system to return a relevant response to the request.

A very basic example of a front controller could be something like this, in PHP (using Apache .htacess redirect rules):

Redirecting all requests to a single .php file (using Apache)

For a typical website that uses a front controller, you will normally want to 'redirect' (not with an actual HTTP location redirect) all requests to a single file.

RewriteCond %{REQUEST_FILENAME} !-f<br>
RewriteCond %{REQUEST_FILENAME} !-d<br>
RewriteRule ^([^?]*)$ /index.php [NC,L,QSA]</p>

The above should be put into a .htaccess file.

The front controller (index.php)

In this super basic example, all requests are routed through index.php. This isn't a good example to follow, but shows a front controller at its most basic. It assumes URLs such as http://yoursite.com/?page=blog, http://yoursite.com/?page=about, etc.

<?php 
if (isset($_GET['page'])) {
$requested_page = $_GET['page'];
}
else {
$requested_page = 'home';
}
// a better way would be to put this into an array, but I think a switch is easier to read for this example
switch($requested_page) {
   case "blog":
      include(__DIR__."/blog.php");
      break;
   case "home":
      include(__DIR__."/home.php");
      break;
   default:
      include(__DIR__."/404.php");
}

Of course, in the real world it would be far less simple.

It is much better to be serving all requests via a front controller (rathe than, in the example above, telling users to go direct to /blog.php) as you can easily make changes in the front controller (index.php, in the example) and apply it to all incoming requests.

Many frameworks, such as Laravel or Symfony use a (much more complicated!) front controller pattern.