Re: [Tracker] Object / RDF storage

[Philip Van Hoof <spam pvanhoof be>]

On Sat, 2009-05-16 at 10:20 +0200, Michele Tameni wrote:

Hi Michele,

> I'm looking for an alternative to use soprano as RDF storage for a
> work that i'm going to do, and i've read that tracker are going to to
> what i need.
> Reading the features page on the site [
> http://projects.gnome.org/tracker/features.html ]  object store seem
> what i need, and reading this page [
> http://live.gnome.org/Tracker/Documentation/AppDevelopersManual ] it
> seam that rdf storage is possibile.

This AppDevelopersManual is outdated.

Most important things that you need to know about for Tracker's first
next release series (the 0.7 release series) is the Nepomuk ontology and
SPARQL as query language.

 o. http://www.semanticdesktop.org/ontologies/
 o. http://www.w3.org/TR/rdf-sparql-query/


o. Right now you simply give the SPARQL query as a "s" (a string over
   DBus) to a method:

   org.freedesktop.Tracker.Resources, /org/freedesktop/Tracker/Resources
   on service org.freedesktop.Tracker (note that these might change in
   future)

   SparqlQuery (query as s) -> result as array of [array of string]


You also have

o. Deleting triples

   Delete (subject, predicate, object)

o. Inserting triples (individual ones)

   Insert (subject, predicate, object)

o. Loading a Turtle file into the store (bulk insert):

   Load (uri as string)

o. Update extension which implements:
   http://jena.hpl.hp.com/~afs/SPARQL-Update.html

   SparqlUpdate


And you have the class signals. The online documentation for this is
updated and available here:

http://live.gnome.org/Tracker/Documentation/SignalsOnChanges



> My question is: in which state is the rdf storage in tracker? there is
> a reusable API for store/get things?

Yes, both (current master is). Current master isn't yet released as a
0.7 version, though. This might happen soon (as a alpha or beta
release).

I don't think that we're ready to guarantee the API for 0.7 yet, as we
are planning to (discuss to) add versioning to the 0.7 API.

SPARQL and Nepomuk are, however, certain.

> there is an api that permit to store object and their metadata that
> allow me to forget rdf?

Note yet for master. Except some of the tools and maybe a few very
simple APIs (get all files that are audio, for example). 

> retriving metadata/object using sparql can be a plus for me.

Cool

> Actually i haven't looked the code, but reading around i hope that
> tracker can do all things i need, but i want a confirm :)

Confirmed


-- 
Philip Van Hoof, freelance software developer
home: me at pvanhoof dot be 
gnome: pvanhoof at gnome dot org 
http://pvanhoof.be/blog
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