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Re: #rdfms-difference-between-ID-and-about

From: Dan Brickley <danbri@w3.org>
Date: Fri, 15 Jun 2001 07:45:10 -0400 (EDT)
To: Graham Klyne <Graham.Klyne@Baltimore.com>
cc: Dan Connolly <connolly@w3.org>, rdf core <w3c-rdfcore-wg@w3.org>
Message-ID: <Pine.LNX.4.30.0106150737050.9767-100000@tux.w3.org>
On Fri, 15 Jun 2001, Graham Klyne wrote:

> At 02:29 AM 6/15/01 -0500, Dan Connolly wrote:
> > > RDF absolutely has to make sense even outside the context of
> > > an enclosing document which can be given a uri. so ...
> >
> >So... what? That doesn't make any sense to me.
> >
> >An RDF document is an XML document. Each XML document
> >has a base URI (cf the infoset spec).
>
> If this is  true, then it is not possible to transfer RDF data in transient
> protocol elements.
>
> Which means that (say) the CC/PP spec, formulated *by design* as a *format*
> only for client capability data, cannot be regarded as a valid RDF application.

Can't we just say that it picks up the base URI from (broadly conceived)
surrounding context? It remains true that each XML document has a base
URI. How we determine that base is the only issue here.


RFC2396 is pretty clear on this. See:
http://www.faqs.org/rfcs/rfc2396.html section 5.1: establishing a base URI

Both XML Protocol and CC/PP use seems to fall under 5.1.2, 'base URI of
the encapsulating entity'. XML:base, by contrast, looks to fall under
'base URI embedded in document's content'.

[[
5.1. Establishing a Base URI
   The term "relative URI" implies that there exists some absolute "base
   URI" against which the relative reference is applied.  Indeed, the
   base URI is necessary to define the semantics of any relative URI
   reference; without it, a relative reference is meaningless.  In order
   for relative URI to be usable within a document, the base URI of that
   document must be known to the parser.
   The base URI of a document can be established in one of four ways,
   listed below in order of precedence.  The order of precedence can be
   thought of in terms of layers, where the innermost defined base URI
   has the highest precedence.  This can be visualized graphically as:
      .----------------------------------------------------------.
      |  .----------------------------------------------------.  |
      |  |  .----------------------------------------------.  |  |
      |  |  |  .----------------------------------------.  |  |  |
      |  |  |  |  .----------------------------------.  |  |  |  |
      |  |  |  |  |       <relative_reference>       |  |  |  |  |
      |  |  |  |  `----------------------------------'  |  |  |  |
      |  |  |  | (5.1.1) Base URI embedded in the       |  |  |  |
      |  |  |  |         document's content             |  |  |  |
      |  |  |  `----------------------------------------'  |  |  |
      |  |  | (5.1.2) Base URI of the encapsulating entity |  |  |
      |  |  |         (message, document, or none).        |  |  |
      |  |  `----------------------------------------------'  |  |
      |  | (5.1.3) URI used to retrieve the entity            |  |
      |  `----------------------------------------------------'  |
      | (5.1.4) Default Base URI is application-dependent        |
      `----------------------------------------------------------'
[...]

]]

Dan
Received on Friday, 15 June 2001 07:45:16 EDT

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