[Xesam] Metadata Storage Daemon

Evgeny Egorochkin phreedom.stdin at gmail.com
Sat Jan 12 06:07:55 PST 2008

В сообщении от Saturday 12 January 2008 12:42:34 Enrico Minack написал(а):
> > 1) A simple metadata storage service over dbus would be quite simple,
> > obviously better API's cost us more time and energy, but the backbone
> > of such a system is extremely rudimentary. I propose that we just go
> > ahead and write one. No desktop search or filters etc. Just a few
> > calls exposed to dbus to store, query and delete Triples (A Combo of
> > some uniqueid, data, and the datatype/metadata). At its core this is a
> > sqlite db with a little extra work.
> so, what you are proposing is a central desktop metadata store which is
> used by beagle (and other applications) to store its data into? Would
> this replace beagle's lucene indices? Or is it a parallel store to
> publish beagle's metadata?

This storage could be provided by 1) an indexer like beagle or it could be 2)a 
standalone app, but naturally it would be very nice for indexers to be able 
to index the storage, so (1) is more likely.

> > Anyways,  Please share API thoughts so we
> > can at least pick a general direction. I would be really interested to
> > know a little more about the more elaborate potential use cases.
> > Honestly, I see 80% of use being:
> > 1) Add lots of attributes for a Uri
> > 2) Query for all attributes associated with a Uri or Query for a
> > specific attribute associated with a Uri
> > 3) Query for Uri sets that have a certain value in a certain
> > attribute. * (This starts to venture into the realm of our indexers
> > obviously this is a regular use case, and we would need it plenty, I'm
> > just noting that any spec we try to make from this should probably
> > _count_ on the other desktop searches indexing their metadata, so we
> > really just filter on them.)
> Also Query for Uri sets that have a keyword in a certain or any
> attribute. This would then be some kind of keyword search over the
> metadata store to get URIs that match the keyword query. With 2) you
> then get all data about the URI.

For settings and stuff, agree.

> What would also be simple to include but will increase ubiquity are
> attributes of URIs that point to other URIs. So the values of metadata
> are not restricted to strings or numbers, but can also be URIs again.

This is indeed useful(sometimes very useful) and turns the whole thing into an 
RDF storage.

-- Evgeny

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