Managing Middleware

By default, this bundle registers server middleware by finding all services with the babdev_websocket_server.server_middleware tag and sorting them by priority.

Below is the list of middleware provided by this bundle and the library and their default priorities:

Adding Middleware

New middleware should be added with a priority lower than 0 as the BabDev\WebSocket\Server\WAMP\Middleware\DispatchMessageToHandler middleware should be the last middleware in the stack.

Middleware added between the WAMP middleware must implement the interface expected by the middleware decorating it:

• Middleware with a priority between -20 and 0 is decorated by the BabDev\WebSocket\Server\WAMP\Middleware\ParseWAMPMessage or BabDev\WebSocket\Server\WAMP\Middleware\UpdateTopicSubscriptions middleware, and must implement BabDev\WebSocket\Server\WAMPServerMiddleware
• Middleware with a priority between -30 and -20 is decorated by the BabDev\WebSocket\Server\WebSocket\Middleware\EstablishWebSocketConnection middleware, and should implement BabDev\WebSocket\Server\WebSocketServerMiddleware and return the sub-protocols of the middleware it decorates from getSubProtocols(); otherwise, the wamp sub-protocol is not supported and clients are rejected when the strict sub-protocol check is enabled

Middleware must have the decorated middleware as the first parameter in the constructor, and cannot use a named parameter in the service definition (i.e. $middleware: !abstract decorated middleware for YAML); this is required for the compiler pass which builds the middleware stack to correctly set the arguments.

The bundle supports autoconfiguration of BabDev\WebSocket\Server\ServerMiddleware classes using the #[AsServerMiddleware] attribute on your middleware class.

<?php declare(strict_types=1);

namespace App\WebSocket\Middleware;

use BabDev\WebSocket\Server\ServerMiddleware;
use BabDev\WebSocketBundle\Attribute\AsServerMiddleware;

#[AsServerMiddleware(priority: -100)]
final readonly class EarlyMiddleware implements ServerMiddleware
{
    public function __construct(
        private ServerMiddleware $middleware,
    ) {}

    /* Class implementation */
}

If you are not using autoconfiguration, the service should be tagged with the babdev_websocket_server.server_middleware service tag and the priority specified.

# config/services.yaml
services:
  App\WebSocket\Middleware\EarlyMiddleware:
    arguments:
      - !abstract decorated middleware
    tags:
      - { name: babdev_websocket_server.server_middleware, priority: -100 }