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Norman Walsh wrote:
> In conversations today on the XML Linking WG, prompted by Erik Wilde's
> proposal for an XLink Data Model[1], I was reminded of another
> possible solution. [...]
>
> This other alternative answer is to use infoset augmentation. By
> modeling linking semantics in terms of additions to the infoset, we
> can make a clear separation between the syntactic constructs used to
> identify links and their meaning.
I think this is an excellent idea.
> So, for example, an HTML browser can construct appropriate link
> information items from HREF, SRC, and LONGDESC attributes in the XHTML
> by appealing to its own understanding of the XHTML vocabulary.
> Similarly, an XLink-aware application can construct them from XLink
> 1.0 attributes.
> As an added bonus, this method allows an application that understands
> links to treat both simple and extended links uniformly. It operates
> on the linking data model without regard to how that was constructed,
> whether the links expressed came originally from simple links in the
> source document or a set of external linkbases.
... or a CSS-like "linking stylesheet," or an AF-like processor,
or a validator, or any number of other pre-processing transformations.
This would allow a lot of flexibility in how XLink could be
applied.
> On the other hand, this is an, uhm, LSI, and is sure to be greeted by
> some with the same enthusiasm as the PSVI :-).
AFAICT, it's not so much the idea of an augmented infoset
that people find disagreeable about the PSVI, it's the
nature (and quantity!) of the data that a W3C XML Schema
validator adds to the Infoset.
Come to think of it, if the Infoset augmentation is expressed
as a set of attributes with a distinguished namespace name,
instead of as a new set of [information item]s, then
the current XLink draft could work unchanged. You just
need to explicitly state that the xlink:* attributes need
not be present in the source document, and may instead
be added by some (unspecified) preprocessing transformation.
--Joe English
jenglish@flightlab.com
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