Dear Roy,
1) URLs could be used for identification, such as URNs. If you store
URLs in your database, make relations to other URIs, and even tag
data with URLs, its perfectly OK, even if the URL is not resolvable,
as quoted from
http://www.w3.org/TR/webarch/:
?Although many URI schemes are named after protocols, this does not
imply that use of such a URI will necessarily result in access to the
resource via the named protocol?
2) Semantic infrastructures will be based on RDF databases where URIs
are stored and could be query via web services using languages like
SPARQL. Similar to what we try do to at MMI with SEMOR, not by
expecting computer-programs to resolve any URL encounter.
3) Having URLs is more human friendly, because humans could learn
more about that URI very fast by just typing the URL in any browser.
This is a human problem !
Best Regards,
-Luis
On Mar 26, 2007, at 12:17 PM, Roy Lowry wrote:
> Dear All,
>
> There seems to be a slight misunderstanding about the crux of the
> debate. The discussion John G and I had last week hinged on the
> identity of the entity represented by the URI. To him it was the
> term: to me it was the phenomenon described by the term.
>
> In the vocabularies I manage, the latter is the case.
> Consequently, I represent the phenomenon by a semantically neutral
> key and feel at liberty to change the term providing I don't change
> the entity it represents (e.g. correcting a spelling error or
> changing syntax). If the term is considered the entity then a
> spelling error would need to be fixed by leaving the error in
> place, putting the correct spelling up as a new term and mapping
> the two terms as synonyms.
>
> In the case of the Standard Names, the governance is strong enough
> for me to be almost convinced that it's OK to consider the term as
> the entity and hence include it in the URI. However, I have
> encountered other vocabularies where terms have changed
> syntactically (usually to clarify semantics) and the previous
> version has simply vanished. If the previous version has been
> deployed in URIs then our semantic infrastructure breaks. To my
> thinking establishing the use of keys fails safe as they are less
> likely to get tweaked in a moment when discipline weakens.
>
> On the URI=URL/URN debate, I'm a pragmatist. I can make practical
> use of a URL today: with a URN I need to find some way of
> describing and implementing business rules to translate URN to
> URL. This is what I imagine registry technology delivers but I see
> this as today's development area, but for the next generation
> operationally.
>
> Finally, I need to make it clear that I would never suggest using a
> meaningless (to humans) URI in CF in place of any existing field
> and am not trying to degrade the self-describing nature of CF. I
> see URIs as extra hooks that open semantics to computers. These
> hooks link into ontologies to form a basis for semantic
> interoperability without forcing everybody to rework their legacy
> data to new standards. This is how I'm planning to bolt SeaDataNet
> and NERC DataGrid together and it would be nice if the result were
> interoperable with CF.
>
> Cheers, Roy.
>
>>>> Jonathan Gregory <j.m.gregory at reading.ac.uk> 03/22/07 5:40 PM >>>
> Dear John
>
> The argument appears to be than an unintelligible identifier (i.e.
> one without
> semantic content) is good because it is in itself meaningless, so
> you have to
> look it up to find out what it means, whereas if you use
> intelligible names,
> you might be misled by misunderstand them. Is that right? I
> appreciate that
> this is rational, but I'm not convinced it is the most helpful
> approach for
> humans. That would be an argument against self-describing netCDF
> files, for
> example. It would argue that the metadata in the files should be
> totally
> cryptic to humans, so that you had the use the latest version of an
> approved
> translator to tell you what it means. That has some attraction, but
> I'm not
> sure it really solves the problem. The translator will use its own
> idioms,
> which the human user will get used to, and if a new version of the
> translator
> gives new meanings to the words it uses, you are back in the same
> problem.
> It seems to me better to admit that one always has be careful at
> some level,
> and use names that have some apparent meaning.
>
> Best wishes
>
> Jonathan
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Received on Mon Mar 26 2007 - 13:51:11 BST
