HTTP lifecycle

Request comes in, PHP runs, response goes out. Frameworks decorate this. They don't replace it.

The loop

In learning mode with the built-in server, public/index.php is the front controller.

Reading the request (raw PHP)

<?php

declare(strict_types=1);

$method = $_SERVER['REQUEST_METHOD'] ?? 'GET';
$uri    = $_SERVER['REQUEST_URI'] ?? '/';
$path   = parse_url($uri, PHP_URL_PATH);

$query = $_GET;  // already parsed query string
$body  = file_get_contents('php://input'); // raw body (JSON APIs)

Comments for the code above:

• $_SERVER, $_GET, $_POST are superglobals - available everywhere (and a bit spooky; frameworks wrap them)
• For JSON APIs, don't use $_POST - parse php://input
• Path vs full URI matters for routing

Writing the response

<?php

declare(strict_types=1);

http_response_code(201);
header('Content-Type: application/json; charset=utf-8');
header('X-Powered-By: curiosity');

echo json_encode(['ok' => true], JSON_THROW_ON_ERROR);

Headers must be sent before body output. Accidental whitespace before <?php will ruin your day ("headers already sent").

Redirects

<?php

declare(strict_types=1);

http_response_code(302);
header('Location: /login');
exit;

Always exit (or return from front controller) after a redirect so you don't keep rendering.

Content negotiation (simple)

<?php

declare(strict_types=1);

$accept = $_SERVER['HTTP_ACCEPT'] ?? 'text/html';

if (str_contains($accept, 'application/json')) {
    header('Content-Type: application/json');
    echo json_encode(['message' => 'hi'], JSON_THROW_ON_ERROR);
} else {
    header('Content-Type: text/html; charset=utf-8');
    echo '<p>hi</p>';
}

Frameworks do this better. Knowing the headers helps when debugging.

Front controller pattern

One entry file:

<?php

declare(strict_types=1);

require __DIR__ . '/../vendor/autoload.php';

// route + dispatch...

Web server rewrites all requests to index.php (Apache RewriteRule, nginx try_files, or php built-in router script). That's how Laravel/Symfony feel like "pretty URLs".

We'll build a tiny version in Mini router.

Compared to Next / Nuxt

Front-end SSR / API routes	Classic PHP
Long-lived or edge runtime	Per-request script / FPM worker
Request / Response objects	Superglobals + header() / echo (or PSR-7 libs)
File-based routing	Explicit router or framework router
Middleware chain	Middleware chain (framework) or manual

Same HTTP. Different packaging.

Best,

-- ł.