public static function isAuthenticated()
{
phpCAS::traceBegin();
phpCAS::_validateClientExists();
// call the isAuthenticated method of the $_PHPCAS_CLIENT object
$auth = self::$_PHPCAS_CLIENT->isAuthenticated();
// store where the authentication has been checked and the result
self::$_PHPCAS_CLIENT->markAuthenticationCall($auth);
phpCAS::traceEnd($auth);
return $auth;
}