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Re: [rdfmsQnameUriMapping-6] Algorithm for creating a URI from a QName in RDF Model?

From: Graham Klyne <GK@ninebynine.org>
Date: Fri, 31 May 2002 12:35:29 +0100
Message-Id: <>
To: Patrick Stickler <patrick.stickler@nokia.com>
Cc: www talk <www-talk@w3.org>

Patrick, I don't really disagree with much of what you say here.  I don't 
plan debate the finer points.  But I'll suggest that even in an open 
network there's a place for proprietary usage.  Many of the more successful 
standards started out as proprietary usage which found a wider audience.

In my case, the /id.../ convention is my way of informally indicating an 
intended usage.  The actual usage will determine the appropriate response 
when trying to retrieve a document.

As for using RDF to expose information about the URI usage within a domain, 
I think that's a fine idea, and another debate.  I don't yet feel the need 
to enter those waters.


At 02:20 PM 5/30/02 +0300, Patrick Stickler wrote:
>On 2002-05-30 12:07, "ext Graham Klyne" <GK@NineByNine.org> wrote:
> > At 09:15 AM 5/30/02 +0300, Patrick Stickler wrote:
> >> On 2002-05-29 15:05, "ext Graham Klyne" <GK@ninebynine.org> wrote:
> >>
> >>> .. (e.g. I have a
> >>> convention in my web space that http://id.ninebynine.org/ is used for 
> such
> >>> abstract identifiers.  I think it helps to clarify the intent, but it
> >>> doesn't make all the problems go away, such as my second question above.)
> >>
> >> Tut, tut, Graham ;-)
> >>
> >> How is this any different from voc://ninebynine.org/... except that the
> >> convention is not standardized and the semantics that the URI denotes an
> >> abstract resource is specific/proprietary to your own practices?
> >
> > Exactly that!
> >
> > It's not standard, and it's something that I as owner of the domain space
> > choose to do.
> >
> > It does nothing to change the universal elements of interpretation of a 
> URI.
>But a human (or software agent) would have to understand the prose
>provided on your site to know that a 404 response was not actually
>a true error, but that the resource is simply not web-accessible.
>I.e. a client that recieves an http: URI expects it to resolve to
>something. It has a traditional interpretation as denoting a web
>accessible resource. If the resource is e.g. the abstract concept
>of "love" then anything that an HTTP server might return with a 1xx
>response is misleading to the client, since that resource itself
>could not be returned, only knowledge about that resource.
>If having 'id.' as part of one of your URLs helps you, fine, but I
>don't intend to try to understand all the internals of site specific
>URLs. I will only concern myself with (a) the semantics defined
>for the specific URI scheme, or (b) knowledge defined about the
>specific resource based on its otherwise opaque URI. (note that
>URI class taxonomies are a disjunct issue entirely)
>Thus if we are to capture in the URI itself whether a given resource
>is or is not web-accessible, it must be done with the URI scheme.
>That's it. What is within the scope of the host domain is not
>interesting or useful with regards to global architecture (and
>specifically should not be).
> >> This seems to conflict with your earlier expressed opinion that the URI
> >> should not reflect itself whether the resource is or is not "on the web"
> >
> > Er, no:  what I said was:
> > [[
> > (By which, I mean that I don't accept them as universal proposals:  I have
> > no argument with their use as a convenient mechanism by you or any other
> > developers. ...
> > ]]
> >
> > I might have added "domain owners".
>Fair enough. Though what if you had a means to expose a portion
>of the semantics of a URI scheme which would apply to all instances
>of that scheme, and do so globally, and in RDF, such that any
>application could obtain that specification and use it to
>interpret any instance of that URI scheme.
>Then, it would not be proprietary, but open and ultimately extensible.
>I.e, just as folks publish DTDs, XML Schemas, RDF Schemas, etc.
>to expose the structure and semantics of content models, so
>one could publish the semantics of a URI scheme that would allow
>all applications to interpret URIs of that scheme consistently,
>yet not have internal native knowledge about the scheme itself.
>So I can, eg. define in RDF that URIs of the scheme voc: denote
>non-web accessible resources, and any application that is presented
>by such a URI then knows that it is meaningless to try to dereference
>that URI. All that is required is a standardized ontology for
>expressing a basic level of semantics about URI schemes useful for
>most web agents needs when dealing with interpretation of URIs.
>On the other hand, in the case of http: URIs which denote non-web
>accessible resources, such knowledge would need to be defined for
>each and every instance, which is a huge maintenance burden. Some
>may prefer or require that level of resolution, but I think most
>folks will prefer to enjoy the economy of URI scheme-wide semantics.
>Still, having metadata specific response codes and methods would
>work in either case. How the server determines the accessibility
>of a resource remains open. It could be based on URI scheme or
>per-resource knowledge.
>Which method one chooses depends on the nature of the resource
>and the abilities/needs of the creator.
>Rather than 100s or 1000s of sites all employing their own
>proprietary URI tricks to reflect whether the denoted resource
>is or is not web accessible, wouldn't it be better to (a) use
>a smaller set of standardized URI schemes to reflect such
>distinctions and (b) express such semantics for those schemes
>in RDF so applications need not maintain such knowledge natively?
>After all, your approach suggests we could forgo schemes such
>as mailto: or ftp: in place of site specific syntactic conventions,
>such as http://mailto.nokia.com/patrick_stickler, etc. because
>the site owner has said somewhere what the nature of such
>resources are.
>There is a clear tradition of distinguishing the accessibility
>characteristics of URIs based on the URI scheme, so why not also
>the non-accessibility characteristics? 'http:' means resolvable
>via HTTP. 'voc:' means not ever resolvable or accessible. Simple,
>clear, concise, consistent, and (ideally) standardized.
>Patrick Stickler              Phone: +358 50 483 9453
>Senior Research Scientist     Fax:   +358 7180 35409
>Nokia Research Center         Email: patrick.stickler@nokia.com

Graham Klyne
Received on Friday, 31 May 2002 08:35:20 UTC

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