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RE: XML:Base - impact on RDF (first pass)

From: Dan Brickley <danbri@w3.org>
Date: Wed, 13 Jun 2001 09:35:42 -0400 (EDT)
To: Ron Daniel <rdaniel@interwoven.com>
cc: RDFCore Working Group <w3c-rdfcore-wg@w3.org>
Message-ID: <Pine.LNX.4.30.0106130917510.4034-100000@tux.w3.org>
On Fri, 8 Jun 2001, Ron Daniel wrote:

> In today's conference call, Aaron pointed out that the XML Base
> spec[BASE] states that it is not retroactive, it is something that
> developers of new XML formats have to decide whether to use.
>
> More specifically, it says:
>
>   The deployment of XML Base is through normative reference by
>   new specifications [...] The behavior of xml:base attributes in
>   applications based on specifications that do not have direct or
>   indirect normative reference to XML Base is undefined.
>
> Our Charter[CHART] says that
>   "The RDF Core WG is neither chartered to develop a new RDF
>    syntax, nor to reformulate the RDF model".
> It also says that
>   "Backwards compatibility with existing RDF applications
>    is a priority for the RDF Core Working Group".
>
> Given those statements, it is pretty clear that the WG has to
> leave xml:base untouched for now. I suggest a resolution
> such as:
>
>   On 2001-06-?? the WG decided that the behavior of the xml:base
>   attribute must remain undefined for the 1.0 RDF Model and Syntax
>   specification. Creators of documents following the 1.0 RDF
>   syntax SHOULD NOT use the xml:base attribute.
>
> Those of us who would like to see it available for use in
> RDF will have to do it somewhere other than in the syntax part
> of a clarified M&S spec.

I've become more sympathetic to this view over the week, and feel I
may have been over enthusiastic for adding xml:base support during last
week's call. That said, I remain very concerned about the deployment
implications should we say that the interaction of xml:base and rdf:RDF
be 'undefined', specifically in mixed-namespace XML documents. The M&S
syntax defines some XML structures that can be used either stand-alone
(with RDF:RDF as the root XML element), or else as part of a larger
mixed-namespace document (eg. in HTML/XHTML). In the latter scenario, the
RDF  syntax specification has to play well with other specs (which may want to
or need to use xml:base; XML Protocols for eg. come to mind...).

In this situation, I wonder if we might explore the idea of revising our
syntax spec so that it distinguishes more clearly between (i) "pure RDF"
XML documents and (ii) "mixed in" documents that include RDF. The former
we have complete control over; the latter are composed according to two or
more specs. I would be happy outlawing xml:base for (i), but in the
context of (ii) we have to accept that xml:base is likely to be used:
these things are beyond our control. TimBL has also (@@ref) previously
raised the need for more clarity regarding the meaning of an XML document
that embeds RDF down inside some other XML elements (eg: in html/head or
html/body/quoted...), so there may be other reasons for sharpening this
distinction.

If we simply say "don't use xml:base" this could be taken as implicitly
telling implementors never to use RDF in a mixed-namespace context since
its interaction with other namespaces in the same doc is undefined. If the
latter is what we mean, I'd like to say that explicitly...

Dan


> Regards,
> Ron
>
> [BASE] http://www.w3.org/TR/xmlbase/
> [CHART] http://www.w3.org/2001/sw/RDFCoreWGCharter
>
>
Received on Wednesday, 13 June 2001 09:35:44 EDT

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