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
