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- From: David Megginson <email@example.com>
- To: "'XML Dev'" <firstname.lastname@example.org>
- Date: Sat, 31 Jul 1999 21:27:00 -0400 (EDT)
Didier PH Martin writes:
> OK, I badly expressed myself. Let's state it differently.
> a) Wasn't XML with the purpose of allow you to create domain
Sure it is, but you don't always want to create them directly on top
of XML; it's good to factor out common constructs into intermediate
layers of abstraction, to simplify the application designers' work.
> d) Was RDF originally intended for meta data?
That was the initial motivation -- after all, the W3C isn't in the
business of general data exchange. However, the spec editors realised
that the distinction is arbitrary:
The distinction between "data" and "metadata" is not an absolute
one; it is a distinction created primarily by a particular
application, and many times the same resource will be interpreted in
both ways simultaneously.
> Was then use a meta data domain language to encode data base records? You
> could have encoded it with your own domain language.
Yes, but then I lose the advantage of being able to use higher-level
APIs to access the information. I could use UTF-8 without XML to
encode my documents, but I like that fact that XML parsers do most of
the work of building a tree out of a character stream; likewise, I
like the fact that RDF processors do most of the work of building
objects out of XML documents.
> In fact, what is useful about rdf is not its elements but more its
> schema part. When XML will have a schema language as good as the
> rdf schema language or if both are united then I guess there is no
> need to use rdf.
That makes very little sense to me. Sure, a schema is interesting,
but an abstracted data-object layer is what will save people time and
expense in building XML systems for data interchange.
> But the original intent of rdf is to add meta data information about
> resources. This is why you have such construct:
> <rdf:description about="http://www.netfolder.com/DSSSL">
> The elements intentionally have the "description about" keywords.
rdf:Description is one particular class; RDF allows the creation of
new classes as well.
All the best,
David Megginson email@example.com
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