[jdev] A case for private XML storage in MUC rooms

[Steve Smith]

Hi,

I'm currently looking at methods of associating multicast addresses and
other metadata with MUC rooms, and I've come to the conclusion that
there is a case for per-room private XML storage, similar to
JEP-0049 ...

How it would work:

The semantics would be virtually identical to the JEP-0049 with the
following exceptions:

        jabber:iq:private stanzas would be sent to the bare JID for the
        MUC room rather than the server
        
        Room members with a role of 'participant' or higher are able to
        retrieve stored XML.
        
        Only the room owner may add, update or delete stored XML.
        (Question: should moderators have this too?)
        
        Stored XML should only be persisted if the room is persisted.
        
        Optionally, updates to stored XML could be broadcast to the
        room, essentially creating a simple per-room pubsub
        implementation.

Why:

I wish to attach persistent meta-data to a room in a manner such that it
is only retrievable by room-participants.  There are other possible
methods of achieving this, but I believe this to have the best
trade-off, so I'll address the alternatives:

        Use service-discovery extensions: This does not provide any
        restriction on who can retrieve the information.  Additionally
        it would create a large overhead, as all data would be returned
        in disco queries.
        
        Add a query namespace for each piece of data: This requires
        implementation of each namespace on the server for what is
        intended to be opaque data.
        
        Use pubsub: A method of specifying the location of the pubsub
        node would still be required, and then additional
        access-restrictions would need to be implemented on the pubsub
        node itself.  In particular the access-restrictions would need
        to be updated to match the changing membership of the room.

        More: There are certainly other angles I haven't considered,
        comments are more than welcome.

Other uses:

There are plenty of cases where a room owner (and moderator?) may wish
to attach useful information to a room in a manner that doesn't require
them to be connected to the room: a longer MOTD than is suitable for a
subject line, room specific bookmarks (using JEP-0048), etc.

I'm going to create an implementation of this in ejabberd if anyone is
interested in playing with it.

Cheers,
Steve