On Monday 21 January 2008, Frederic V. Hessman wrote:

> - suggest using either a "hash namespace" (e.g. "http://myvocab.org/
> myvocab-v1.1#mytoken"), a "slash namespace" (e.g. "http://
> yourvocab.net/yourvocab-v1.1/mytoken") or a 303-redirect service; all
> three proposals are out there and have their points.  I believe the
> "hash" variety is simpler to understand and configure (for small
> vocabularies, and we all agree we want many small vocabularies rather
> than a few gigantic ones).  If the congnicenti think that all the GET
> requests for distinguishing between contents are far enough along,
> then the "slash" variety may make it easier to query individual
> entries (e.g. HTML docs rather than RDF), something which appears to
> be  harder using "hash".  The point is to make a single mechanism
> standard - at least at first, when there are enough other things to
> worry about.  When the semantic web finally chooses a standard, we
> can still adopt it then (if we haven't already).

I'm pretty sure both will remain. It is a matter of preference, both has 
their place. Indeed, if you maintain a relatively small vocabulary and 
want to use a single file, it is easier to use a hash namespace. If you 
have a URI for a single abstract concept, I might be inclined to use a 
303 URI in some cases. 

But the really interesting thing to do when using 303 URIs is when it is 
backed by a SPARQL Endpoint. Then, you can just send the 303 to the 
SPARQL Endpoint as a DESCRIBE query and get the RDF back.

For example, you have a URI http://astro.example.org/objects/Q0957+561 
that identifies the Twin Quasar. If someone GETs this URI, of course, 
they can't get the Twin Quasar, since that's far away, so you give them 
a 303, which redirects to 
http://astro.example.org/sparql?query=DESCRIBE<http://astro.example.org/objects/Q0957+561>

A DESCRIBE query practically means "give me everything you know about 
this object, within a boundary", so a description of the object is 
returned. This is becoming a popular way to do things, and one that I 
can recommend.

> - Looked at a few parsers (e.g. HP's Jena for Java) but still can't
> judge whether there are enough flexible parsers out there to be able
> to say it doesn't matter whether a publisher uses XML, N3 or Turtle

I don't think it does. Almost all tools support those three now, and now 
that the two latter are "W3C Team Submissions", they have a firm enough 
footing for implementers. The only tool I've dumped into that had 
problems with N3 is Protege, but I would be surprised if it didn't gain 
that support soon.

If I write RDF/OWL by hand, I usually write N3 or Turtle, but I often 
use RDF/XML when using software serialisers.

Cheers,

Kjetil
-- 
Kjetil Kjernsmo
Programmer / Astrophysicist / Ski-orienteer / Orienteer / Mountaineer
kjetil at kjernsmo.net
Homepage: http://www.kjetil.kjernsmo.net/     OpenPGP KeyID: 6A6A0BBC

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