Sample server-side script for PHP

Copy the following into a .php file:

<?php
// Define list of valid barcodes
// NOTE: This you might want to replace with a database query (or a file lookup) to look up if the given barcode is valid.
//       You might also want to register in your database or a file that the barcode was sent here to the server.
$valid_barcodes = [
	'8576482874',
	'2475587348',
	'4203716559',
	'9184783714',
	'1486424882',
	'2845717594',
	'2118477499',
];

// Validate incoming data
if (empty($_GET['data'])) {
	system_error('No barcode sent to server.');
}
if (empty($_GET['id'])) {
	system_error('No scanner ID sent to server.');
}

// Check if barcode is valid
if (in_array($_GET['data'], $valid_barcodes)) {
	header('Content-Type: application/json');
	echo json_encode(['status' => 'ok', 'result_msg' => 'Everything is good! Welcome to the show!']);
} else {
	system_error('Barcode is invalid.');
}

// --------------------------------------------------------------
// Utility functions

function system_error($err_msg) {
	header('Content-Type: application/json');
	echo json_encode(['status' => 'error', 'err_msg' => $err_msg]);
	exit;
}