[Xesam] Metadata Storage Daemon

Jamie McCracken jamie.mccrack at googlemail.com
Tue Jan 15 07:05:35 PST 2008


On Tue, 2008-01-15 at 15:51 +0100, Sebastian Trüg wrote:
> On Saturday 12 January 2008 00:05:38 Mikkel Kamstrup Erlandsen wrote:
> > On 11/01/2008, Sebastian Trüg <strueg at mandriva.com> wrote:
> > > Just my 2 cents:
> > > Soprano has a IMOH very good DBus API [1] for RDF storage which fulfills
> > > all 3 of your requirements below. We already use it for Nepomuk and it
> > > works great. And since Xesam is already using URIs to identify stuff why
> > > not go the extra mile to RDF storage altogether?
> >
> > I thought Soprano depended on Qt?
> 
> That has nothing to do with the D-Bus interface. I thought we were looking for 
> an API?
> 
> > Anyways, I don't think the RDF quadruples is a good thing to expose
> > directly to the programmers who just want a quick and dirty metadata
> > storage. It is simply just too technical. That does not mean that we
> > cannot use that stuff under the hood though.
> >
> > > Timestamps are handled via named graphs [2], also known as context (RDF
> > > quadruples).
> >
> > Are you suggesting putting the mtime in the name of each RDF triple?
> > If we are to support timestamps I don't think we should expose them as
> > RDF quadruples because I still think that it is too much abstraction
> > to present to the end user developer.
> 
> No, named graphs mean that each triple becomes a quadruple and the forth node 
> is used to group triples together into subgraphs. These subgraphs are then 
> annotated with arbitrary information such as creation date.
> 


it (quad-store) sounds quite bloated

would it not be better to have a single metadata_changed_timestamp
attribute on the entity itself rather than on each and every triple/quad
metadata item?

jamie



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