XML-Data: advantages over DTD syntax?

Jonathan Robie jwrobie at mindspring.com
Wed Oct 1 13:27:44 BST 1997

At 10:13 AM 10/1/97 BST, Henry S. Thompson wrote:
>Without responding to the details of Murray and Len's exchange, two
>1) Murray is of course right that the logic of content models is not
>made any easier by changing their notation;
>2) Complexity is in the eye of the beholder, and the advantage to the
>user of being able to use the SAME graphical UI to construct both
>instance and schema might be taken to operate in favour of the schema
>approach in this area.

Of course, if such an editor were designed using a Design Patterns approach,
with a common abstract base class for the methods used to construct a DTD or
a document, you could have the same thing. However, I'm not sure that I
would *want* to construct the XML-Data schemas the same way I create XML
documents - it looks like there would still be a fair amount of typing, more
than I need to create a DTD.

Of course, it *would* be nice to have graphical tools for creating DTDs
which explicitly show the inheritance relationships. But I don't see how an
alternative syntax helps me to create such tools.

>Note:  I am not now nor have I ever been a Microsoft employee, nor is
>Steve De Rose.  Microsoft paid for my trip to Redmond during which
>the foundations for the XML-Data document were laid, but they don't
>own or operate me.
>I've learned by working with our co-authors at Microsoft and their
>colleagues that there are people in Redmond who lack horns and are
>both technically competent and genuinely interested in standards.

I do not believe that Microsoft owns you or Steve De Rose, nor that
Microsoft employees are inherently evil.

>Accordingly, I'd be greatful if those commenting on this document
>could avoid the cheap rhetorical device of referring to "the Microsoft
>approach", implying thereby that it shouldn't be taken seriously
>because we all know that Microsoft are {only in it for the money,
>aiming at world domination, fundamentally duplicitous, . . .}, and
>concentrate on technical issues.

I find it interesting how much you read into the phrase "the Microsoft
approach" - after all, it *is* an approach advocated by Microsoft, as
opposed to the approach which has been accepted by standardization
committees. I really do see great value in having a standard approach, and
one which is supported by tools like SP, Jade, etc. The standardization
committees are there to ensure these standard approaches. Now if I look at
the XML White Paper from Microsoft's "Standards" page for information on
XML, it does not even mention the industry-standard DTDs, instead, it tells
me "Microsoft has proposed a 'Document Type Definition' (DTD) syntax for
expressing the schema for an XML document directly within XML itself,
allowing XML data to describe its own structure. Expressing schemata within
XML adds great power to the XML format because it makes it possible for
software examining certain data to understand its structure without earlier
knowledge about the data or its meaning." To me, it looks as though they are
championing this as an alternative to DTDs. In fact, someone who did not
already know about DTDs would have no idea that they exist in XML, or that
the term 'Document Type Definition' were not invented by Microsoft. I know
that you do not represent Microsoft, but I do think that Microsoft's
marketing materials indicate a desire to support XML-Data instead of DTDs,
and I am concerned about the possibility of a split in the industry similar
to the Java wars that we are now experiencing.

I would like to see a lot of the functionality of Architectural Forms or
XML-Data in SGML/XML, and I would like to see it supported by standards.
Does XML-Data do anything that XML with HyTime would not do? Is it only an
alternative syntax?


Jonathan Robie   jwrobie at mindspring.com  http://www.mindspring.com/~jwrobie
POET Software, 3207 Gibson Road, Durham, N.C., 27703    http://www.poet.com

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