$request_params = array(
'message' => "Hello, {$user_name}!",
'user_id' => $user_id,
'access_token' => $token,
'v' => '5.0'
);
$get_params = http_build_query($request_params);
file_get_contents('https://api.vk.com/method/messages.send?'. $get_params);
echo('ok');
break;
}