protected function computeAffiliateId($visitorId, $accountId) {
     $singleVisitorProcessor = new Pap_Tracking_Visit_SingleVisitorProcessor($visitorId, $accountId);
     $params = new Gpf_Rpc_Params();
     $params->add('visitorId', $visitorId);
     $params->add('accountId', $accountId);
     $affiliateData = $singleVisitorProcessor->getAffiliate($params);
     return $affiliateData->getValue('userid');
 }