No-Framework PHP Knowledge Base

Quick reference for building framework-free PHP applications using PSR standards, standalone Composer packages, and Clean Architecture. Covers everything needed to run a production-grade project without Symfony, Laravel, or any full-stack framework.

Core Principles

PSR Compliance

nyholm/psr7

guzzlehttp/psr7

php-di/php-di

league/container

relay/relay

nyholm/psr7

monolog/monolog

symfony/cache

Key Advantages

• Maximum domain freedom — Domain layer is pure PHP by default
• Composable packages — pick exactly the libraries you need
• Full control — bootstrap, middleware, error handling are explicit
• Lightweight — no hidden magic, no auto-wiring unless configured

Architecture Stack

public/index.php (Front Controller) → Middleware Pipeline (PSR-15)
  → Presentation (Actions) → Application (Use Cases) → Domain (Entities/VOs)
  → Infrastructure (Repos/Adapters) ← Composer + PSR-4 Autoloading

Quick Checklists

DDD-Compatible Pure PHP Project

• declare(strict_types=1)

  in every file
• PSR-4 autoloading via Composer
• Domain layer has zero external

  use

  statements (no Doctrine, no framework)
• Repository interfaces in Domain, implementations in Infrastructure
• DI container configured explicitly (PHP-DI or League)
• PSR-7 request/response, PSR-15 middleware pipeline
• Front controller in

  public/index.php

• Environment config via

  .env

  +

  vlucas/phpdotenv

• Error handling middleware with custom exception hierarchy
• Security via JWT middleware (lcobucci/jwt) + RBAC; Domain uses Specifications for authorization
• Queue job handlers delegate to Application UseCases; Domain dispatches events, not jobs
• Infrastructure components (Cache, HTTP Client, Mailer) accessed via domain port interfaces
• Domain EventDispatcherInterface port; Infrastructure provides PSR-14 or InMemory adapter

Clean Architecture Checks

• No

  use Illuminate\\

  or

  use Symfony\\

  in Domain or Application layers
• No HTTP concepts in Application layer
• All external services accessed through port interfaces
• Compiled DI container in production
• Database migrations managed by standalone tool

Common Violations Quick Reference

declare(strict_types=1)

require

include

$_GET

$_POST

$_SESSION

src/Domain/**/*.php

src/Infrastructure/**/*.php

echo

header()

public/index.php

src/Application/**/*.php

new

index.php

public/index.php

src/Domain/**/*.php

use Enqueue\\

use PhpAmqpLib\\

CacheInterface

HttpClientInterface

PHP 8.4 No-Framework Patterns

PSR-15 Middleware

declare(strict_types=1);

namespace Infrastructure\Http\Middleware;

use Psr\Http\Message\{ResponseInterface, ServerRequestInterface};
use Psr\Http\Server\{MiddlewareInterface, RequestHandlerInterface};

final readonly class CorsMiddleware implements MiddlewareInterface
{
    public function __construct(private string $allowedOrigin = '*') {}

    public function process(ServerRequestInterface $request, RequestHandlerInterface $handler): ResponseInterface
    {
        return $handler->handle($request)
            ->withHeader('Access-Control-Allow-Origin', $this->allowedOrigin)
            ->withHeader('Access-Control-Allow-Methods', 'GET, POST, PUT, DELETE');
    }
}

Application Service (Use Case)

declare(strict_types=1);

namespace Application\Order\UseCase;

final readonly class PlaceOrderUseCase
{
    public function __construct(
        private OrderRepositoryInterface $orders,
        private EventDispatcherInterface $events,
    ) {}

    public function execute(PlaceOrderCommand $command): OrderId
    {
        $order = Order::create($command->customerId, $command->lines);
        $this->orders->save($order);

        foreach ($order->releaseEvents() as $event) {
            $this->events->dispatch($event);
        }

        return $order->id();
    }
}

Front Controller

declare(strict_types=1);

require dirname(__DIR__) . '/vendor/autoload.php';
Dotenv\Dotenv::createImmutable(dirname(__DIR__))->load();
$container = require dirname(__DIR__) . '/config/container.php';
$container->get(App::class)->run();

References

For detailed information, load these reference files:

• references/architecture.md

  — Project structure, PSR-4 autoloading, bootstrap patterns

• references/ddd-integration.md

  — Pure Domain layer, Value Objects, Entities, Domain Events

• references/routing-http.md

  — PSR-7/PSR-15 HTTP, routing, middleware pipeline

• references/persistence.md

  — Doctrine/Cycle standalone, PDO repositories, migrations

• references/dependency-injection.md

  — PHP-DI, League Container, PSR-11, compiled containers

• references/testing.md

  — PHPUnit standalone, mocking, HTTP testing, database testing

• references/antipatterns.md

  — Common no-framework mistakes with detection patterns

• references/security.md

  — JWT authentication (lcobucci/jwt), RBAC middleware, password hashing, CSRF, security headers

• references/event-system.md

  — PSR-14, league/event, custom dispatcher, domain events, async event processing

• references/queue.md

  — enqueue/enqueue, php-amqplib, workers, job dispatcher, supervisor

• references/infrastructure-components.md

  — Cache PSR-6/16, HTTP Client PSR-18, Mailer, Rate Limiting