PSR-7 and Symfony


Kévin Dunglas

Kévin Dunglas

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At the beginning, HTTP messages

GET /2015/06/using-psr-7-in-symfony/?user=kevin HTTP/1.1
Accept: text/html
User-Agent: Kevin using Telnet
HTTP/1.1 301 Moved Permanently
Date: Tue, 07 Jul 2015 21:34:25 GMT
Transfer-Encoding: chunked
Connection: keep-alive
Set-Cookie: __cfduid=dbe0ddf9f8fa7b7379b4a3b0e2fe9b3871436304865; expires=Wed, 06-Jul-16 21:34:25 GMT; path=/;; HttpOnly
Server: cloudflare-nginx
CF-RAY: 2026ac574100014c-CDG

Marshalling is repetitive and relatively hard to do.

CGI variables, SAPI, superglobals

if (isset($_GET['user']) && 'kevin' === $_GET['user']) {
    syslog(LOG_INFO, 'Kevin was here');

echo 0;

A first abstraction layer

Practical but...

  • hard to test
  • coupled to superglobals
  • not object oriented

Then, higher abstraction layers

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

$request = Request::createFromGlobals();
$response = new Response('Hello');
$response->headers->setCookie(new Cookie(
    $request->get('user', 'anonymous')

Symfony HttpFoundation

Introduced in Symfony 2.0. Used by Laravel, Drupal, phpBB, eZ Publish...

7M downloads for the standalone component. + almost 7M for the full stack framework.

But other implementations exists

  • Guzzle Messages
  • Zend\Http
  • ReactPHP Messages
  • CakePHP Network HTTP
  • Buzz Messages
  • ...

These implementations are not interoperable.

PHP Framework Interoperability Group (PHP FIG)

  • Symfony
  • Zend Framework
  • Laravel
  • Drupal
  • eZ Publish
  • phpBB
  • ...

Publish PHP Standard Recommendations (PSR).

PSR-7: HTTP Messages Interfaces

  • Message: MessageInterface
  • Request: RequestInterface
  • CGI-like style: ServerRequestInterface
  • Response: ResponseInterface
  • Uploaded File: UploadedFileInterface
  • Stream (bodies and files): StreamInterface
  • URI: UriInterface

Using PSR-7 interfaces

/** @var $request \Psr\Http\Message\ServerRequestInterface */
$queryParams = $request->getQueryParams();
if (isset($queryParams['user']) {
    echo htmlspecialchars($queryParams['user']);

/** @var $response \Psr\Http\Message\ResponseInterface */
$response->withHeader('X-Foo', 'bar');

Differences with HttpFoundation

  • Immutability (with*() methods)
  • Almost everything is stream
  • Designed to work for servers and clients (think about Guzzle)
  • Different API

PSR-7 implementations

PSR-7 support in Symfony

  • Introduced in Symfony 2.7
  • Backported for Symfony 2.3+
  • First major framework to support PSR-7
  • Use a converter between HttpFoundation and PSR-7
  • Zend Diactoros has default PSR-7 implementation


composer require symfony/psr-http-message-bridge zendframework/zend-diactoros

A converter?

  • Implementing PSR-7 interfaces in HttpFoundation is not possible without BC break (immutability)
  • Work In Progress (with BC break but with upgrade path) for Symfony 3.0
  • The converter has a negative performance impact

PSR-7 in Symfony Standard Edition

namespace AppBundle\Controller;

use Psr\Http\Message\ServerRequestInterface;
use Symfony\Bundle\FrameworkBundle\Controller\Controller;
use Zend\Diactoros\Response;

class DefaultController extends Controller
    public function indexAction(ServerRequestInterface $request)
        $parsedBody = $request->getParsedBody(); // $_POST content
        if (isset($parsedBody['message']) {
            // Yeah, it's PSR-3 here

        $response = new Response();

        $response->getBody()->write('Hello world');
        $response = $response->withHeader('X-Best', '');

        return $response;

Symfony to PSR-7 Request

use Symfony\Bridge\PsrHttpMessage\Factory\DiactorosFactory;
use Symfony\Component\HttpFoundation\Request;

$symfonyRequest = new Request(/* ... */);
// The HTTP_HOST server key must be set to avoid an unexpected error

$psr7Factory = new DiactorosFactory();
$psrRequest = $psr7Factory->createRequest($symfonyRequest);

Symfony to PSR-7 Response

use Symfony\Bridge\PsrHttpMessage\Factory\DiactorosFactory;
use Symfony\Component\HttpFoundation\Response;

$symfonyResponse = new Response(/* ... */);

$psr7Factory = new DiactorosFactory();
$psrResponse = $psr7Factory->createResponse($symfonyResponse);

PSR-7 to HttpFoundation Request

use Symfony\Bridge\PsrHttpMessage\Factory\HttpFoundationFactory;

/** @var $psrRequest \Psr\Http\Message\ServerRequestInterface */

$httpFoundationFactory = new HttpFoundationFactory();
$symfonyRequest = $httpFoundationFactory->createRequest($psrRequest);

PSR-7 to HttpFoundation Response

use Symfony\Bridge\PsrHttpMessage\Factory\HttpFoundationFactory;

/** @var $psrResponse \Psr\Http\Message\ResponseInterface */

$httpFoundationFactory = new HttpFoundationFactory();
$symfonyResponse = $httpFoundationFactory->createResponse($psrResponse);

Current PSR-7 adoption

  • Symfony 2.3+ (you got it)
  • Guzzle 6
  • Laravel 5.1 (using the Symfony Bridge)
  • Silex 1.2 (using the Symfony Bridge)
  • Drupal 8 (beta - using the Symfony Bridge)
  • Slim 3 (beta)
  • Zend Framework 3 (future)

Interoperable PHP middleware

Middleware Schema
Credits: StackPHP

Existing middleware solutions

In other languages:

  • WSGI (Python)
  • Rack (Ruby)
  • Sencha Connect (Node.js)


A Stratigility middleware

function myStratigilityMiddleware(
    \Psr\Http\Message\ServerRequestInterface $request,
    \Psr\Http\Message\ResponseInterface $response,
    callable $next = null
    ) {
        $response->getBody()->write('Hello from Stratigility');

        return $next($req, $res);

Used in a Symfony controller

class MyController {
    public function indexAction(\Psr\Http\Message\ServerRequestInterface $request)
        $response = new \Zend\Diactoros\Response();

        return myStratigilityMiddleware($request, $response, function ($req, $res) {
            return $res;

Or in a Symfony event

use Symfony\Bridge\PsrHttpMessage\Factory\DiactorosFactory;
use Symfony\Bridge\PsrHttpMessage\Factory\HttpFoundationFactory;
use Symfony\Component\HttpKernel\Event\GetResponseEvent;

public function onKernelRequest(GetResponseEvent $event)
    if (!$event->isMasterRequest()) {

    $httpFoundationFactory = new HttpFoundationFactory();
    $diactorosFactory = new DiactorosFactory();

        function ($req, $res) use ($event) {


  • PSR-7 is awesome for interoperability at the library level
  • Symfony use a converter to support PSR-7
  • it allows to use PSR-7 middleware with Symfony HttpFoundation based libraries
  • the other side is true too
  • for performance reasons: if you don't need it, don't use it


PHP beer