Re: Proposing Tracker for inclusion into GNOME 2.18



2006-10-25 klockan 03:11 skrev James Henstridge:
> On 25/10/06, Jamie McCracken <jamiemcc blueyonder co uk> wrote:
> > We shouldn't need a flattened table as the two metadatatype tables would
> > be properly indexed so joins would be fast (especially with sqlite)
> 
> Really?  From the description I give above, the relationships between
> different metadata types form a directed graph.  Taking the music
> example again, consider the following set of relationship types:
>  1. foo performed bar
>  2. foo performed vocals on bar
>  3. foo performed lead vocals on bar
> 
> If I register that (2) is a subclass of (1) and (3) is a subclass of
> (2), I want searches for relationship type (1) to pick up metadata of
> types (1), (2) and (3).

The RDFS Entailment Rules [1] may help inferring triples without the need
for complete reasoning support.

> Ideally this would be mostly invisible to users: their queries for
> generic relationship types would just work, even if the metadata
> extractors for particular file types produced more specialised types.
> 
> It does mean that application authors who wish to introduce new types
> of metadata need to think about how they relate to the existing types,
> but that is necessary for the metadata to stay useful when doing
> generic queries.

Just use rdfs:subPropertyOf to a well-known type (eg. Dublin Core) and
you're safe, afaics.


  mvrgr, Wouter

[1] http://www.w3.org/TR/2004/REC-rdf-mt-20040210/#rules
-- 
:wq                                                       mail uws xs4all nl
                                                      web http://uwstopia.nl

well i'm happy when it's good :: and when it's bad i cry          -- the who

Attachment: signature.asc
Description: Digital signature



[Date Prev][Date Next]   [Thread Prev][Thread Next]   [Thread Index] [Date Index] [Author Index]