function payload()
    {
        if ( $this->IsFault )
        {
            $payload = xmlrpc_encode( array(
                "faultCode" => $this->FaultCode,
                "faultString" => $this->FaultString ) );
            return str_replace( array( '<fault>', '</fault>' ), array( '<methodResponse><fault>', '</fault></methodResponse>' ), $payload );
        }
        else
        {
            $payload = xmlrpc_encode( $this->Value );
            /// @todo verify if user gave us back an array with faultString / faultCode members,
            ///       as we will be sending back junk in that case...
            return str_replace( array( '<params>', '</params>' ), array( '<methodResponse><params>', '</params></methodResponse>' ), $payload );
        }
    }