Kingsley,
thanks for your email, i know that an URI can be an URL or an URN. In case of an URN the exact meaning is not at once clear, the
definition is not at once accessible,
it is even possible (http://dbooth.org/2008/irsw/) that there are "competing definitions". This is not good for information
transfer, so it is plausible
to reduce step by step the application of this concept.
It is better to use a *special* ULR (you may call this a "LURN": a "Linked URN"
because it defines an object like a name using a
link) which points to (a file with pointers to) (multilingual) definitions and
further associated information.
A simple example: let "xxx-length" denote some URN. Then we may conclude, the
following number describes the length of some object.
But we don't know the unit. So we need special knowledge or to search for the
exact definition.
It would be much more efficient , if we have a link (e.g.
"dn/xxx-length-info-pointer") to a file which at once allows you to find
the exact definition in your language (and templates for human readable
representation, metrics for similarity search, as
mentioned).
In future more and more special application may be considered. For example in
medicine you need a huge vocabulary. Immediate access
to exact definitions is highly desirable.
So it seems plausible to prefer step by step in future URLs (which are "LURNs")
instead of URNs.
Wolfgang
----- Original Message -----
From: "Kingsley Idehen" <[email protected]>
To: "W. Orthuber" <[email protected]>
Cc: "semantic-web" <[email protected]>; "Linked Data community"
<[email protected]>
Sent: Thursday, May 21, 2009 5:42 PM
Subject: Re: URLs instead of URNs (Was URI lifecycle (Was: Owning URIs))
W. Orthuber wrote:
David,
In short, although semantic web architecture could be designed to permit
unrestricted semantic drift,
I think it is a better design -- better
serving the semantic web community as a whole -- to adopt an
architecture that permits the semantics of each URI to be anchored, by
use of a URI declaration.
Absolutement.
Yes, I think also, URIs should be well defined. Up to now I thought they are,
but your article shows that URIs (which are not
URLs)
have not necessarily an unique definition! Moreover URI should be anchored; the
best would be that they contain a link to all
their
definition and further bindingly associated information.
A URI is a Uniform Resource Identifier. A global identifier mechanism network
addressable data items. Its sole function is Name
oriented Identification.
A URL is a Resource Location Identifier. Its *typical* function is Resource
Address/Location Identification combined with Data
Access mechanism.
David describes an HTTP based URI which by essence *can* embody both of the
functions above -- subject to use of HTTP messaging
heuristics (between user agents and servers) for disambiguating between the
Identity/Name or Address/Access functions.
Hope this provides clarity.
I do agree that the definition and relationship between URIs and URLs remain a
source of distracting confusion; especially, when
speaking outside the Semantic Web community.
Kingsley
Why not prefer URIs which are (special "defining") URLs, which contain a link
to a file which contains links to all defining
information (unambiguous
information, in multiple languages if wished)?
So the anchor would be at once accessible and there would be exactly one
location for the decisive information.
Best
Wolfgang
----- Original Message ----- From: "Hugh Glaser" <[email protected]>
To: "David Booth" <[email protected]>
Cc: "semantic-web" <[email protected]>; "Linked Data community"
<[email protected]>
Sent: Wednesday, May 20, 2009 11:21 PM
Subject: Re: URI lifecycle (Was: Owning URIs)
Hi David,
On 20/05/2009 06:01, "David Booth" <[email protected]> wrote:
A last comment, which I know we have discussed, and you possibly disagree:
"Community expropriation of a URI"
Might have meant something else.
One of the problems is that many authors will not discharge their Statement
Author Responsibilities, but will assume that the URI is the one they want.
Over time, this may mean that the general SW uses a URI in a way other than
the URI owner intends, to the extent that it becomes irrelevant what was the
original meaning (there are many parallels for this in natural language, and
indeed it is the social process that causes language to change).
[ . . . ]
Yes, that's a great topic for discussion. It is clear that semantic
drift is a natural part of natural language: a word that meant one thing
years ago may mean something quite different now. As humans we can
usually deal with this semantic drift by knowing the context in which a
word is used, though it can cause real life misunderstandings sometimes.
However, I think our use of URIs in RDF is different from our use of
words in natural language, in two important ways:
- RDF is designed for machine processing -- not just human
communication -- and machines are not so good at understanding context
and resolving ambiguity; and
- with URI declarations there is a simple, feasible, low-cost mechanism
available that can be used to anchor the semantics of a URI.
In short, although semantic web architecture could be designed to permit
unrestricted semantic drift, I think it is a better design -- better
serving the semantic web community as a whole -- to adopt an
architecture that permits the semantics of each URI to be anchored, by
use of a URI declaration.
Absolutement.
But your paper is not about architecture.
The architecture, as you say, permits the semantics of each URI to be
anchored.
The (one of the?) good thing about your paper is that it is about the stuff
that is not enforced by the architecture, but rather addresses what might be
called the social processes and what responsibilities might be.
And works hard to avoid confusion between them.
So if one was to envisage ways in which the consequences of failure to
adhere to the responsibilities might have a significant impact, and how that
impact might be accommodated or challenged, then I think it can be useful to
study it.
I happen to think that people and hence agents will simply assume they know
what URIs mean without checking the anchor, in the same way they use words
without checking the dictionary. If I was marking this email up in RDFa, I
would be much more likely to guess, or simply go and use the URIs you had
used to mark up your email, rather than check each one back at base - I
would never be able to do anything if I checked every word in the
dictionary.
In fact, how much of all the RDFa that is now being generated gets checked?
I do take your point that a lot of this is happening with machines, but even
they will make the same mistake when choosing a URI.
Best
Hugh
For more explanation see: "Why URI Declarations? A comparison of
architectural approaches"
http://dbooth.org/2008/irsw/
--
David Booth, Ph.D.
Cleveland Clinic (contractor)
Opinions expressed herein are those of the author and do not necessarily
reflect those of Cleveland Clinic.
--
Regards,
Kingsley Idehen Weblog: http://www.openlinksw.com/blog/~kidehen
President & CEO OpenLink Software Web: http://www.openlinksw.com
