Understand what is transmitted to Itilium?

Question

1C-Bitrix

$endpoint='https://'.$_SERVER['HTTP_HOST'].'/sd/itilium-import/ws.php';
    $wsdlCreator=new NWSDLCreator("SDTask",$endpoint,"path/Itilium");
    $wsdlCreator->operations=[
      new WSDL\TaskAccomplices(),
      new \WSDL\TaskAuditors(),
      new \WSDL\TaskBPNote(),
      new \WSDL\TaskComment(),
      new \WSDL\TaskGetByID(),
      new \WSDL\TaskGetTaskComments(),
      new \WSDL\TaskTrudoz(),
      new \WSDL\TaskUpdate(),
                        new \WSDL\TaskChangeWorkGroup(),
      new \WSDL\TaskAccessInfo()
    ];
    header("Content-Type: text/xml;charset=utf-8");
    echo $wsdlCreator->createWSDL();
    exit();
  }
  
  $_SERVER["REQUEST_METHOD"] = "POST";
  
  $server = new CSOAPServer();
  
  $contents=file_get_contents("php://input");
  
  $taskId="";
  if (preg_match("`taskId[^>]*>(\d+)`",$contents,$m)) {
    $taskId=".".$m[1];
  }
  
  file_put_contents(__DIR__."/log/".date("Y.m.d H-i-s").$taskId.".in.xml",$contents);
  
  $resp=new NSoapResponser();
  $server->AddServerResponser($resp);
  
  
  $server->ProcessRequest();

I can't figure out what exactly is being sent. The meaning is that after a certain period of time, Itilium knocks on this file and starts the function for data transfer, but what volumes are not clear. I can't figure out where to start