Re: [xml-dev] Are URNs deprecated?

["Norman Gray" <norman@astro.gla.ac.uk>]

Roger, hello.

On 17 Aug 2016, at 18:01, Costello, Roger L. wrote:

> Does "the use of the term has been deprecated" mean that URNs have 
> been deprecated?
It's not that URNs are deprecated -- they never really existed in a 
meaningful sense!

The original URI RFC (RFC 2396 ?) divided URIs into URLs, which 
specifically indicated a _location_, and URNs, which provided a name for 
a resource, but not a location.  The intuition was, I think, that URNs 
provided a persistent name without a commitment to resolving it, whereas 
URLs had an operational effect.  These were both, in some hand-wavy 
sense, subclasses of 'URI'.

But the distinction never really mattered: there's nothing about a URN 
(so called -- roughly anything which wasn't an http:// URL) which 
guarantees that the name can be resolved, and there's nothing 
intrinsically transient about a URL.  The important thing about a URL, 
from the point of view of its long-term usefulness, is whether it is 
backed by an "institutional commitment to persistence" (I think this 
phrase is Stuart Weibel's,; or it may have been John Kunze).  Something 
under purl.org or under id.loc.gov has an "institutional commitment to 
persistence" which is worth an awful lot more than any amount of 
indirection that you get through a fancy URI scheme.  As Stuart (or 
whoever) said , "loc.gov isn't going away any time soon".

The fact that purl.org is currently looking very shaky demonstrates that 
that institutional commitment is not a magic guarantee.  But there's no 
magic in 'urn:', either.

RFC 3968 <https://www.ietf.org/rfc/rfc3986.txt> mentions that '[a] URI 
can be further classified as a locator, a name, or both', and that 
'[t]he term "Uniform Resource Name" (URN) has been used historically to 
refer to both URIs under the "urn" scheme', but that 'Future 
specifications and related documentation should use the general term 
"URI" rather than the more restrictive terms "URL" and "URN".'

All the best,

Norman


--
Norman Gray  :  https://nxg.me.uk
SUPA School of Physics and Astronomy, University of Glasgow, UK