08 Hello HTTP

Goal

Run a PHP script that serves the text hello at http://localhost:8000/hello, using only the built-in server — no framework, no third-party router.

Prerequisites

• Functions

Two Ways PHP's Built-in Server Handles Requests

1. Direct file mapping (what 01 Install PHP's checkpoint used): a request to /hello.php runs hello.php directly. Fine for one-off scripts, but every route needs its own file.
2. Router script: pass a single PHP file to php -S, and every request — regardless of path — runs through that file first. The script inspects $_SERVER['REQUEST_URI'] and decides what to do. This is how the rest of this tier's JSON API will route requests.

What a Router Script Looks Like

$_SERVER is a superglobal — an associative array PHP populates automatically with request metadata, always available, no import needed. $_SERVER['REQUEST_URI'] holds the requested path (e.g. /hello).

Code

Create router.php:

<?php

$path = $_SERVER['REQUEST_URI'];

if ($path === '/hello') {
    echo "hello\n";
} else {
    http_response_code(404);
    echo "not found\n";
}

Run it:

php -S localhost:8000 router.php

You should see:

[Sat Jan  1 00:00:00 2026] PHP 8.3.6 Development Server (http://localhost:8000) started

In a second terminal:

curl http://localhost:8000/hello

Output:

hello

Try an unmapped path:

curl -i http://localhost:8000/nope

You should see HTTP/1.1 404 Not Found in the headers, followed by not found.

Stop the server with Ctrl-C.

http_response_code(404) sets the HTTP status code for the response — the router script controls both the routing decision and the status, exactly the two things a framework's routing layer would otherwise handle for you.

Checkpoint

Extend router.php with a second route (/status) that returns a different message, and confirm both /hello and /status respond correctly while everything else still 404s.

Next

Continue to 09 JSON Encoding.