PortalEventsToolProposal

I am proposing to add a new tool, portal_events, to the set of top-level tools provided by each portal. This tool would be a CORBA-style event channel, supporting the following interfaces:

  class PortalEventSource:
      def register( observer ):
          """ Register an event sink for future notification.

              observer
must be a traversable path to an
                object conforming to the PortalEventSink interface.
          """

      def unregister( observer ):
          """ Unegister an event sink to prevent future notification.

              observer
must be a traversable path to an
                object conforming to the PortalEventSink interface.
          """

  class PortalEventSink:
      def notify( eventType, payload=None, **kw ):
          """ Process an event from an event source.

              eventType
meant to be easily tested for filtering;
                may be a well-known constant, a class object, etc.
              payload
event data (or a lazy proxy therefore).
              kw
meta-data about the event, especially useful
                for filtering.

              Implementations of this interface contract to handle
              these notifications "quickly", without blocking.
          """

Here are the events I foresee flowing through portal_events:

• ObjectManagers? within the portal will notify the tool when objects are added or removed (the portal_catalog will subscribe to get these).

• PortalContent will notify the tool when saving changes (the portal_catalog can subscribe to this one, too).

• The portal_registration tool will notify of newly-added members.