Odoo XML-RPC Traceback (most recent call last) - php

Question

I'm new one on Odoo, and I don't have experience with the system and try to follow the documentation how they do it.
For my first thing what I need is to connect external PHP web application whit our Odoo system.
I see this is possible and I follow the steps on that documentation: Odoo Documentation
So I'm stick here:
$common = ripcord::client("$url/xmlrpc/2/common");
$common->version();
When I execute that lines of code I get that error:
[faultString] => Traceback (most recent call last):
File "/home/odoo/src/odoo/12.0/odoo/addons/base/controllers/rpc.py", line 63, in xmlrpc_2
response = self._xmlrpc(service)
File "/home/odoo/src/odoo/12.0/odoo/addons/base/controllers/rpc.py", line 42, in _xmlrpc
params, method = loads(data)
File "/usr/lib/python3.5/xmlrpc/client.py", line 1000, in loads
p.close()
File "/usr/lib/python3.5/xmlrpc/client.py", line 447, in close
parser.Parse(b"", True) # end of data
xml.parsers.expat.ExpatError: no element found: line 1, column 0
I use demo URL (https://demo.odoo.com/) which their recommend. And from first example I get username, password, database name, successfully. But after that I cannot do anything.
UPDATE:
That is my PHP class which I call for testing:
require_once(__DIR__ . '/Ripcode/ripcord.php');
class Ripcode
{
private $_url = 'https://demo.odoo.com/';
private $_server = [];
private $_connection = null;
private $_common = null;
public function __construct()
{
$this->_server = \ripcord::client($this->_url . 'start')->start();
$common = \ripcord::client($this->_url . "xmlrpc/2/common");
$common->version();
$models = \ripcord::client($this->_url . "xmlrpc/2/object");
$uid = $common->authenticate(
$this->_server['database'],
$this->_server['user'],
$this->_server['password'],
array()
);
showArray([
'server' => $this->_server,
'uid' => $uid
]);
showArray([
'server' => $this->_server,
'models' => $models,
'uid' => $uid
'common' => $common->version()
]);
}
}

Answer 1

The problem is ripcord. I tested one cloned from https://github.com/poef/ripcord with an Odoo v12 running locally and debugged from the reception of the request all the way through until the response is sent. Everything works seamlessly until it gets to ripcord.
May I suggest using another XML-RPC client?