HttpFoundation defines an object-oriented layer for the HTTP specification.

It provides an abstraction for requests, responses, uploaded files, cookies, sessions, ...

In this example, we get a Request object from the current PHP global variables:

use Symfony\Component\HttpFoundation\Request;
use Symfony\Component\HttpFoundation\Response;

$request = Request::createFromGlobals();
echo $request->getPathInfo();

You can also create a Request directly -- that's interesting for unit testing:

$request = Request::create('/?foo=bar', 'GET');
echo $request->getPathInfo();

And here is how to create and send a Response:

$response = new Response('Not Found', 404, array('Content-Type' => 'text/plain'));
$response->send();

The Request and the Response classes have many other methods that implement the HTTP specification.

If you are not using Composer but are using PHP 5.3.x, you must add the following to your autoloader:

// SessionHandlerInterface
if (!interface_exists('SessionHandlerInterface')) {
    $loader->registerPrefixFallback(__DIR__.'/../vendor/symfony/src/Symfony/Component/HttpFoundation/Resources/stubs');
}

You can run the unit tests with the following command:

$ cd path/to/Symfony/Component/HttpFoundation/
$ composer.phar install
$ phpunit