Re: RDF Concepts and fragids

Jonathan Rees wrote:
> Poking around the blogosphere I came across this:
> 
> http://www.w3.org/TR/rdf-concepts/#section-fragID
> 
> which seems to contradict 3986 and webarch.  According to this text,
> if I have id="foo" in an XML document (not rdf+xml) at
> http://example/x, then http://example/x does NOT refer to that XML
> element, as it would according to 3986 and webarch.
> 
> Worse, if there's RDF at that URI published as Turtle, then the Turtle
> can't specify the meaning of a fragid, because Concepts says that
> RDF/XML semantics applies.
> 
> What a rathole!
> 
> Nathan, I trust you'll be fixing this. Somehow. :)

Thanks for that!

RFC3023, XML media type [ http://www.ietf.org/rfc/rfc3023.txt ] says:

    Section 4.1 of [RFC2396] notes that the semantics of a fragment
    identifier (the part of a URI after a "#") is a property of the data
    resulting from a retrieval action, and that the format and
    interpretation of fragment identifiers is dependent on the media type
    of the retrieval result.

    As of today, no established specifications define identifiers for XML
    media types.

(so undefined)

RFC 3986, URI [ http://www.ietf.org/rfc/rfc3986.txt ] says:

    The fragment identifier component of a URI allows indirect
    identification of a secondary resource by reference to a primary
    resource and additional identifying information.  The identified
    secondary resource may be some portion or subset of the primary
    resource, some view on representations of the primary resource, or
   *some other resource defined or described by those representations.*

(so it can be anything defined or described by)

RFC 3870, RDF media type [ http://www.ietf.org/rfc/rfc3870.txt ] says:

    The rdf:ID and rdf:about attributes can be used to define fragments
    in an RDF document.

(which defines rdf:ID and rdf:about as defining attributes, not @id)

and http://www.w3.org/TR/rdf-concepts/#section-fragID says:

    eg:someurl#frag means the thing that is indicated, according to the
    rules of the application/rdf+xml MIME content-type as a "fragment"
    or "view" of the RDF document at eg:someurl. If the document does not
    exist, or cannot be retrieved, or is available only in formats other
    than application/rdf+xml, then exactly what that view may be is
    somewhat undetermined, but that does not prevent use of RDF to say
    things about it.

    the RDF treatment of a fragment identifier allows it to indicate a
    thing that is entirely external to the document, or even to the
    "shared information space" known as the Web. That is, it can be a
    more general idea, like some particular car or a mythical Unicorn.

(which on my read, is aligned with URI and web arch).

So, Turtle isn't a rec w/ a mime type yet, and when it does it'll define 
things inline w/ RDF, URI and Web Arch. XML doesn't define @id as being 
for fragments (that I can see), so unsure what the issue is? (other than 
brushing up on wording and references to related specs).

Best,

Nathan

Received on Friday, 1 April 2011 23:11:28 UTC