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MiddlewarePipe

The core middleware pipeline implementation that manages the execution order and delegation of middleware components.

Overview

MiddlewarePipe is the central component that orchestrates middleware execution in the cmd-bus system. It maintains a queue of middleware components and ensures they execute in the correct order (FIFO - First In, First Out).

Class Definition

final class MiddlewarePipe implements MiddlewarePipelineInterface
{
    /** @var SplQueue<MiddlewareInterface> */
    private SplQueue $pipeline;

    public function __construct();
    public function __clone();
    public function handle(CommandInterface $command): mixed;
    public function process(CommandInterface $command, CommandHandlerInterface $handler): mixed;
    public function pipe(MiddlewareInterface $middleware): void;
}

Constructor

Creates a new middleware pipeline with an empty queue.

public function __construct()
{
    $this->pipeline = new SplQueue();
}

Methods

handle(CommandInterface $command): mixed

Processes a command through the entire pipeline, using an EmptyPipelineHandler as the fallback handler.

Parameters:

  • $command - The command to process

Returns:

  • mixed - The result from the pipeline execution

process(CommandInterface $command, CommandHandlerInterface $handler): mixed

Processes a command through the pipeline with a specific final handler.

Parameters:

  • $command - The command to process
  • $handler - The handler to use when the pipeline is exhausted

Returns:

  • CommandResultInterface - The result from the pipeline execution

pipe(MiddlewareInterface $middleware): void

Adds middleware to the end of the pipeline queue.

Parameters:

  • $middleware - The middleware to add

__clone()

Performs a deep clone of the pipeline queue to ensure cloned instances have independent pipelines.

Usage Examples

Basic Pipeline Setup

use Webware\CommandBus\MiddlewarePipe;
use App\Middleware\LoggingMiddleware;
use App\Middleware\ValidationMiddleware;
use Webware\CommandBus\Middleware\CommandHandlerMiddleware;

$pipeline = new MiddlewarePipe();

// Add middleware in execution order
$pipeline->pipe(new LoggingMiddleware($logger));
$pipeline->pipe(new CommandHandlerMiddleware($handlerFactory));

// Process a command
$result = $pipeline->handle($command);

Pipeline Execution Flow

The middleware pipeline executes in FIFO order:

  1. First Middleware - Executes first (highest priority)
  2. Second Middleware - Called by first middleware
  3. Third Middleware - Called by second middleware
  4. Final Handler - Called when pipeline is exhausted

Related Components