Botman能够拨打第三方网络服务吗？

Hi I am trying the BotMan Chat. How do I connect to the web service from Bot Man? Who is able to help me with this issue?

I am getting uncaught (in promise) error:

Request failed with status code 500.

$client = new GuzzleHttpClient();
$appurl ='http://<aasdfasdffafa>/webservice/rest/server.php?wstoken=FELrRaBd1rLH5G8KJtrLgctDIfbPHTS7&wsfunction=core_user_get_users_by_field&field=username&values[0]=ramkee&moodlewsrestformat=json';
$res = $client->request('GET',$appurl);
$results = json_decode($res->getBody(),true);
foreach($results as $name => $data) {
    $d=var_dump($data['username']); 
}

Thanks.