This document introduces PHP applications based on middleware and PSR-7. It discusses the PSR-7 standard for HTTP messages, which defines request and response objects. It also covers PSR-15 for server middleware, where each middleware in the chain can process the request and decide whether to pass it to the next middleware. Examples are provided of common middleware like caching, routing, and authorization middleware. Finally, it lists some frameworks that use this middleware approach like Zend Expressive, Slim, and Stack PHP.

1. Introducción a aplicaciones PHP
basadas en Middleware y PSR-7
Alejandro Celaya — @acelayaa

2. PHP Framework Interop Group
Proponen recomendaciones de estándar.
PSR-7 - HTTP Messages
PSR-15 - Server middleware
PHP-FIG

3. PSR-7 - HTTP Messages
El estándar HTTP de ne dos tipos de mensajes:
Request y Response
PHP está orientado hacia la web, y usa HTTP
PSR-7 propone que Request y Response sean
inmutables

4. Middleware
Gestión del proceso de resolución de un request a
través de capas o middlewares.
Cada middleware decide si invocar al siguiente en la
lista.

5. Firmas del middleware
Double-pass: Request + Response
Single pass: Request (PSR-15)
El response debería modi carse sólo en el camino de
salida.
public function __invoke(
Request $reqest,
Response $response,
callable $next
): Response;
public function process(Request $reqest, Delegate $next) : Response;

6. Arquitectura middleware
Imágen de Zend Expressive Docs

7. Cache middleware
public CacheMiddleware implements MiddlewareInterface
{
public function process(RequestInterface $request, DelegateInterface $delegate)
{
// If this route is already cached, return cached content
$cacheKey = (string) $request->getUri();
if ($this->cache->contains($cacheKey)) {
$body = new Stream('php://temp', 'rw');
$body->write($this->cache->fetch($cacheKey))
return (new Response())->withBody($body);
}
// If this route has not been cached yet, process it and cache the result
$resp = $delegate->process($request);
$this->cache->save($cacheKey, (string) $resp->getBody());
return $resp;
}
}

8. Routing middleware
public RoutingMiddleware implements MiddlewareInterface
{
public function process(Request $request, DelegateInterface $delegate)
{
$route = $this->router->match($request);
// If no route was found, return not found error
if ($route === null) {
return (new Response())->withStatus(404);
}
$request = $request->withAttribute('route', $route);
return $delegate->process($request);
}
}

9. Authorization middleware
public AuthorizationMiddleware implements MiddlewareInterface
{
public function process(Request $request, DelegateInterface $delegate)
{
$route = $request->getAttribute('route');
$resource = $route->getRouteName();
$role = $this->determineCurrentUserRole();
// If the role is allowed to access the resource, process next middleware
if ($this->acl->isAllowed($role, $resource)) {
return $delegate->process($request);
}
// If the role is not allowed to access the resource, return a forbidden response
return (new Response())->withStatus(403);
}
}

10. Frameworks basados en middleware
Zend Expressive (Stratigility)
Slim framework v3
Stack PHP
Relay PHP
Spiral framework
Middleman

11. Enlaces de interés
Expressive:
Slim:
Stack:
PHP-FIG:
PSR-7 spec:
PSR-15 spec:
PSR-7 middleware:
PSR-15 middleware:
https://docs.zendframework.com/zend-expressive/
https://www.slimframework.com/
http://stackphp.com/
http://www.php- g.org/
http://www.php- g.org/psr/psr-7/
https://github.com/php- g/ g-
standards/blob/master/proposed/http-middleware/middleware.md
https://github.com/oscarotero/psr7-middlewares
https://github.com/middlewares/awesome-psr15-
middlewares

12. Conclusión

13. ¿Preguntas?