XSchema: ease of use (design goal 5)
cowan at locke.ccil.org
Tue Jun 2 17:47:53 BST 1998
Michael Kay wrote:
> I think the most important point this paper states (and
> demonstrates) is:
> >human beings will find them [XSchemas] painful to write by
> hand, due to their great redundancy compared to DTDs.
> This conflicts directly with design goal 5, which states:
> >XSchema documents shall be easy to create, read, and
> modify, and shall
> provide authoring support.
The emphasis here should be on "by hand". Writing XML documents
of any sort without machine support is painful. XED, to take
the lowest common denominator, makes a big difference here.
> When I first looked at the idea of encoding DTDs in XML a
> couple of months ago, one of my motivations was that I find
> the current DTD syntax very ugly, and I came to the same
> conclusion: whatever the merits of an XML encoding, it would
> not be user-friendly. (My feelings about XSL are the same).
> XML works well as a markup language for text; it also works
> well as a markup language for data; but it is very poor as a
> human-readable lexical encoding of a language with rich
I agree, if for "readable" you substitute "writable". Proper
indentation conventions and other such things can make reading
easier. But then, syntax-coloring editors can make writing
> * we can imagine a "pre-parser" which takes an RXML document
> and automatically generates additional XML markup so that
> all the syntax is now fully accessible as elements and
> attributes. This pre-parsed document would no longer be
> easily readable, but it would be easily processable using
> standard XML tools
Actually, I think XML-DTD syntax is fine for the purpose.
Write DTDs, translate to XSchemas; that's what I did when writing
the draft itself to produce the Meta-XSchema.
> * We could encode both the current DTD information and the
> additional constraints in RXML
Unfortunately it's hard to know how far to go. There is
a trivial XML encoding of DTDs something like this:
<DTD><![CDATA] insert the DTD here ]]></DTD>
and there is a slippery slope of just how much to encode as
elements and attributes, and how much to leave in DTD format.
John Cowan http://www.ccil.org/~cowan cowan at ccil.org
You tollerday donsk? N. You tolkatiff scowegian? Nn.
You spigotty anglease? Nnn. You phonio saxo? Nnnn.
Clear all so! 'Tis a Jute.... (Finnegans Wake 16.5)
xml-dev: A list for W3C XML Developers. To post, mailto:xml-dev at ic.ac.uk
Archived as: http://www.lists.ic.ac.uk/hypermail/xml-dev/
To (un)subscribe, mailto:majordomo at ic.ac.uk the following message;
To subscribe to the digests, mailto:majordomo at ic.ac.uk the following message;
List coordinator, Henry Rzepa (mailto:rzepa at ic.ac.uk)
More information about the Xml-dev