if ( isset( $request->headers['x-siteaccess'] ) )
       {
           $siteaccessName = $request->headers['x-siteaccess'][0];
           if ( !isset( $this->siteAccessList[$siteaccessName] ) )
           {
               unset( $this->siteAccess );
               throw new InvalidSiteAccessException( $siteaccessName, array_keys( $this->siteAccessList ), 'x-siteaccess request header' );
           }

           $this->siteAccess->name = $siteaccessName;
           $this->siteAccess->matchingType = 'header';
           return $this->siteAccess;
       }