/**
  *  Logs in user on Adobe Connect server using external authentication
  * 
  * @ilObjUser $ilUser
  *
  * @param  $user
  * @return String       Session id
  */
 public function externalLogin($user)
 {
     if ($this->adcInfo->getAuthMode() == ilAdobeConnectServer::AUTH_MODE_HEADER) {
         $auth_result = $this->useHTTPHeaderAuthentification($user);
         return $auth_result;
     } else {
         $auth_result = $this->usePasswordAuthentification($user);
         return $auth_result;
     }
 }