🐘 PHP example

<?php
$endpoint = 'https://bbb.example.com/bigbluebutton/api';
$secret   = 'YOUR_SHARED_SECRET';

// 1) Build create params (query string)
$params = [
  'name'  => 'Demo with Overrides',
  'meetingID' => 'demo-123',
  'attendeePW' => 'ap',
  'moderatorPW'=> 'mp',
  'allowOverrideClientSettingsOnCreateCall' => 'true',
];
$query = http_build_query($params);

// 2) Compute checksum for create
$checksum = sha1('create' . $query . $secret);
$url = "{$endpoint}/create?{$query}&checksum={$checksum}";

// 3) Build POST body (XML with JSON inside CDATA)
$override = [
  'public' => [
    'app' => ['appName' => 'Greenlight', 'helpLink' => 'greenlight.example.com'],
    'defaultSettings' => [
      'application' => ['autoJoin' => true, 'askForConfirmationOnLeave' => false],
      'user' => ['userSettingsStorage' => 'sessionStorage', 'application' => ['overrideLocale' => 'en']],
    ],
  ],
];
$json = json_encode($override, JSON_UNESCAPED_SLASHES);
$xmlBody = "<modules><module name=\"clientSettingsOverride\"><![CDATA[{$json}]]></module></modules>";

// 4) POST it
$ch = curl_init($url);
curl_setopt_array($ch, [
  CURLOPT_POST => true,
  CURLOPT_HTTPHEADER => ['Content-Type: application/xml'],
  CURLOPT_POSTFIELDS => $xmlBody,
  CURLOPT_RETURNTRANSFER => true,
]);
$response = curl_exec($ch);
if ($response === false) {
  throw new \RuntimeException('cURL error: ' . curl_error($ch));
}
curl_close($ch);

header('Content-Type: text/xml');
echo $response;