HTTP & APIs — yttcom.net

What happens when curl calls a PHP endpoint. Requests, responses, GET, POST, and JSON — explained from scratch.

What is HTTP?

HTTP is the language browsers and servers use to talk to each other. Every time you open a webpage, your browser sends an HTTP request to a server. The server sends back an HTTP response. That exchange is HTTP.

GET vs POST — the two main request types

GET — asking for something. The data travels in the URL itself, after a ?. Used for reading.

POST — sending something. The data travels inside the request body, hidden from the URL. Used for writing, saving, or anything sensitive.

// GET — data visible in URL // https://yttcom.net/file_read.php?token=abc&file=test.txt $file = $_GET["file"]; // "test.txt" $token = $_GET["token"]; // "abc" // POST — data in request body (not in URL) // curl -X POST -F "token=abc" -F "content=hello" $token = $_POST["token"]; // "abc" $content = $_POST["content"]; // "hello"

What is an API?

API stands for Application Programming Interface. It sounds complicated but the idea is simple: an API is a PHP file (or set of PHP files) that other programs can talk to — not humans, but code.

When Builder runs a curl command to deploy a file, it is talking to the yttcom.net API. The API receives the request, does something, and sends back a structured response.

curl command on Claude's server ↓ sends POST request file_write_web.php on yttcom.net ↓ checks token, writes file JSON response back to Claude ↓ {"status":"ok","bytes":4423} Claude reads response, reports result

JSON — the language APIs speak

JSON is a simple way to structure data so that any program can read it. It uses curly braces for objects and square brackets for lists.

// A JSON response from yttcom.net looks like this: { "status": "ok", "message": "File written successfully", "bytes": 4423 } // PHP creates JSON with json_encode() $response = ["status" => "ok", "bytes" => 4423]; echo json_encode($response); // outputs: {"status":"ok","bytes":4423} // PHP reads JSON with json_decode() $raw = '{"status":"ok","bytes":4423}'; $data = json_decode($raw, true); // true = give me an array echo $data["status"]; // ok

Sending headers — setting up the response

Before PHP sends any output, it can set headers — metadata about the response. The most important ones for APIs are Content-Type (telling the caller what format the response is in) and CORS (telling the browser which websites are allowed to call this endpoint).

<?php // These MUST come before any echo or output header("Content-Type: application/json"); header("Access-Control-Allow-Origin: https://yttcom.net"); header_remove("X-Powered-By"); // hide PHP version echo json_encode(["status" => "ok"]);

HTTP status codes — the response number

Every HTTP response includes a number that tells the caller whether the request worked. You have seen these in your browser.

200 // OK — worked fine (default) 403 // Forbidden — wrong token or not allowed 404 // Not Found — file or endpoint doesn't exist 429 // Too Many Requests — rate limit hit 500 // Server Error — PHP crashed // In PHP: http_response_code(403); die(json_encode(["status" => "error", "message" => "Unauthorized"]));

The full call cycle — yttcom.net example

1. Builder runs: curl -X POST file_write_web.php -d "token=..." -d "path=..." -d "content=..."
2. yttcom.net receives the POST request
3. PHP reads $_POST["token"] and checks it
4. PHP reads $_POST["path"] and $_POST["content"]
5. PHP writes the file to disk
6. PHP sends back: {"status":"ok","bytes":4423}
7. Builder reads the response and confirms success

Every endpoint on yttcom.net follows this exact pattern.