HttpFoundation

HttpFoundation is a PHP library that provides an object-oriented representation of HTTP messages. It is the HTTP foundation component of the Symfony framework but is distributed independently as the symfony/http-foundation package, making it usable in non-Symfony projects as well. The component is widely adopted in PHP ecosystems, including Laravel and Drupal, for handling HTTP requests and responses in a framework-agnostic way.

The two central classes are Request and Response. The Request class encapsulates data from an HTTP request, including query parameters, request body (POST data), attributes used by routing, cookies, uploaded files, and server information. It can be created from PHP’s global variables via Request::createFromGlobals() or constructed manually for testing. The Response class represents the HTTP response to be sent to the client, including status code, headers, and content. It provides methods to set headers, cookies, and content, and a send() method to deliver the response to the client.

In addition to these, HttpFoundation provides supporting classes such as UploadedFile, Cookie, HeaderBag, ParameterBag, ServerBag, and Session-related utilities (including a RequestStack for managing multiple concurrent requests). These components collectively offer a cohesive API for reading, validating, and modifying HTTP data.

Usage and integration: In Symfony applications, HttpFoundation underpins the HTTP kernel and routing flow, translating a Request into a Response. It is also used in other PHP projects as a standalone tool for building and manipulating HTTP messages in a consistent, testable way.

History and compatibility: The component has evolved with Symfony since the early 2010s and remains a core, widely used library. It is compatible with modern PHP versions and can be extended with bridges to other standards, such as PSR-7, via additional packages.