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RE: RDF and xml:base

From: Ron Daniel <rdaniel@interwoven.com>
Date: Wed, 30 May 2001 09:07:47 -0700
To: "Lee Jonas" <lee.jonas@cakehouse.co.uk>, "'Graham Klyne'" <GK@ninebynine.org>
Cc: "RDF Interest" <www-rdf-interest@w3.org>
Message-ID: <EMEKICCGFEKJFGKMFLEPMELHCKAA.rdaniel@interwoven.com>
Hi Lee,

You asked:

> I can't seem to find any mention of resolving URI-references to 
> documents in the current XPointer draft.  It seems to only 
> describe how to address fragments within an XML resource 
> (presumably, once it has been resolved and fetched).

The XPointer drafts don't specify how to resolve a reference to a documents,
that is all defined in other specs (principally RFC 2396). XPointer just
defines the fragment identifier syntax for XML documents.

> Anyhow, the XPointer draft lists RFC 2396 as a "normative" 
> reference, yet the treatment of fragments you describe would go 
> against the established treatment of fragments as outlined in the 
> RFC.  Why?  Is it an oversight?

Um, if what I was describing DOES go against RFC 2396, it would be an error
and would need to be fixed. But I don't think it does.


> Again, from RFC 2396, section 5.2:
> [[
> 
>    For each URI reference, the following steps are performed in order:
> 
>    1) The URI reference is parsed into the potential four components and
>       fragment identifier, as described in Section 4.3.
> ]]
> 
> i.e. scheme, authority, path and query parts of the URI, plus 
> possibly a fragment identifier.
> 
> [[
>    2) If the path component is empty and the scheme, authority, and
>       query components are undefined, then it is a reference to the
>       current document and we are done.  Otherwise, the reference URI's
>       query and fragment components are defined as found (or not found)
>       within the URI reference and not inherited from the base URI.
> ]]
> 
> i.e. a fragment on its own => "it is a reference to the current 
> document and we are done".

Right, but Section 5.2 actually starts by saying:

> 5.2. Resolving Relative References to Absolute Form
> 
>   This section describes an example algorithm for resolving URI
>   references that might be relative to a given base URI.
>
>   The base URI is established ACCORDING TO THE RULES OF SECTION 5.1 and
>   parsed into the four main components as described in Section 3.  

(emphasis added)

Section 5.1 says that the highest priority way of determining the
base URI is:

> 5.1.1. Base URI within Document Content
> 
>    Within certain document media types, the base URI of the document can
>    be embedded within the content itself such that it can be readily
>    obtained by a parser.  

which will be xml:base for XML documents (once it becomes a REC).

So, if xml:base is specified, it is what is parsed into the components.

Ron



Received on Wednesday, 30 May 2001 12:09:42 GMT

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