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.
You can run the unit tests with the following command:
$ cd path/to/Symfony/Component/HttpFoundation/
$ composer install
$ phpunit