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Re: temporary urn:predicates

From: Urs Holzer <urs@andonyar.com>
Date: Mon, 13 Jul 2015 16:42:10 +0200
To: Melvin Carvalho <melvincarvalho@gmail.com>
Cc: Semantic Web <semantic-web@w3.org>
Message-ID: <20150713144210.GA4899@speedy.localnet>
On Mon, Jul 13, 2015 at 03:51:11PM +0200, Melvin Carvalho wrote:
> On 13 July 2015 at 15:42, Urs Holzer <urs@andonyar.com> wrote:
> 
> > On Tue, Jun 30, 2015 at 04:59:29PM +0200, Melvin Carvalho wrote:
> > > I was talking recently about barriers to producing semantic web data.
> > >
> > > Normally a predicate has to be
> > >
> > > - A URI
> > > - Preferably an HTTP URI
> > > - Preferably an existing URI
> > >
> > > This (Im told) can be a barrier for newcomers.  They have to find the
> > right
> > > name for a predicate, the right URI, and then see if it's already used.
> > If
> > > not create their own vocabulary.
> > >
> > > At this point some might give up.
> > >
> > > So I was wondering how it might be possible to create a temporary URI
> > that
> > > people could use as a place holder, so the software still works, until
> > they
> > > think of a better name.
> > > [...]
> >
> > One can use a UUID URN as a namespace: http://tools.ietf.org/html/rfc4122
> > For example <urn:uuid:19b75eab-77bd-46a7-a9c6-1ff0fd135a56#>
> >
> 
> Thanks, yes I use this.
> 
> 
> >
> > There is also a URN namespace for examples:
> > http://tools.ietf.org/html/rfc6963
> >
> >
> It seems to me that when a variable is "just a name" then urn: as a URI
> being "just a name" seems a very good fit.
> 
> I've had a look at some, but not all, of the sub namespaces within URN.  It
> seems hard to pick one over the other, and that the top level of urn: was
> designed for exactly this use case, and therefore, could be the easiest
> place to build consensus around ... I could be wrong!

http://tools.ietf.org/html/rfc2141 indicates to me that a urn needs a
namespaces identifier (and consequently contains at least two colons).
The required Syntax is
	<URN> ::= "urn:" <NID> ":" <NSS>
So, I would not use <urn:>.

http://tools.ietf.org/html/rfc3406 reserves all URN namespaces beginning
with X- for experimental purposes.

Finally you could also coin your own URI scheme, for example <private:>,
but see http://tools.ietf.org/html/rfc7595#section-3.8

I would suggest <example:> if the data is not published before removing
all <example:> with proper URIs. Otherwise, if it is used in a larger
context and the temporary URIs are replaced gradually, I would use UUID
URNs ensuring uniqueness. <example:> has the advantage that one can
locate them with a simple search. A URN may always be legitimate, so it
would become more difficult later on to find out which URIs still have
to be replaced with proper ones.
Received on Monday, 13 July 2015 14:42:40 UTC

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