docs: def save_xml(self, doc, element):
          '''Save this data port into an xml.dom.Element object.'''
          element.setAttributeNS(XSI_NS, XSI_NS_S + 'type', 'rtsExt:dataport_connector_ext')
          element.setAttributeNS(RTS_NS, RTS_NS_S + 'connectorId',
                                 self.connector_id)
          element.setAttributeNS(RTS_NS, RTS_NS_S + 'name', self.name)
          element.setAttributeNS(RTS_NS, RTS_NS_S + 'dataType', self.data_type)
          element.setAttributeNS(RTS_NS, RTS_NS_S + 'interfaceType',
                                 self.interface_type)
          element.setAttributeNS(RTS_NS, RTS_NS_S + 'dataflowType',
                                 self.data_flow_type)
          if self.subscription_type:
              element.setAttributeNS(RTS_NS, RTS_NS_S + 'subscriptionType',
                                     self.subscription_type)
          if self.push_interval != 0.0:
              element.setAttributeNS(RTS_NS, RTS_NS_S + 'pushInterval',
                                     str(self.push_interval))
          if self.comment:
              element.setAttributeNS(RTS_EXT_NS, RTS_EXT_NS_S + 'comment',
                                     self.comment)
          if self.visible != True:
              element.setAttributeNS(RTS_EXT_NS, RTS_EXT_NS_S + 'visible',
                                     str(self.visible).lower())
          new_element = doc.createElementNS(RTS_NS, RTS_NS_S + 'sourceDataPort')
          self.source_data_port.save_xml(doc, new_element)
          element.appendChild(new_element)
          new_element = doc.createElementNS(RTS_NS, RTS_NS_S + 'targetDataPort')
          self.target_data_port.save_xml(doc, new_element)
          element.appendChild(new_element)
          for p in self.properties:
              new_prop_element = doc.createElementNS(RTS_EXT_NS,
                                                     RTS_EXT_NS_S + 'Properties')
              properties_to_xml(new_prop_element, p, self.properties[p])
              element.appendChild(new_prop_element)