Questions on DCD

[Arnold, Curt]

Curt.Arnold at hyprotech.com on 10/02/98 12:18:44 PM
>>Instead of adding another parser, why wasn't the constraint specified
as
>>XML.  i.e.

>From: Dean Roddey [mailto:roddey at us.ibm.com]
>I thought about that but I also thought about what I as a user would
want to
>actually have to use and I thought that that was just so wordy that I'd
not
>want to use it myself unless forced to. The other syntax is more
comprehensible
>to the human reader/writer in my opinion, takes up less bulk in the DOM
tree,
>and is really just as easy to parse in its raw form since the form is
so simple.

>Of course it won't be my decision and I just put the idea out there to
get it
>discussed. I'm sure that whatever gets done I'll probably not agree
with it :-)

One downside is that the DTD can't validate the constraints formulation
(unless you have a custom constraint that checks constraints, but that
is pretty circular).  Schema authors are a fairly rarified bunch, so I
wouldn't be enormously concerned about a few extra keystrokes (we will
program our editors to do it for us, or when we finally get useful
DTD-aware editors, it would auto-complete the elements for us).  I would
think the parser authors would bypass DOM creation so I don't see DOM
space as being a huge issue.  

I was a little taken back by my quick look into VML, which basically did
the same thing.  Once you got beyond a shape, the descriptions of the
shape looked like HP plotter commands.

One thing that we are doing is adding an documentation fragments to that
we can process DCD and generate HTMLHelp manuals for the schemas we are
developing.  Doing constraints as XML elements, would give us somewhere
to explain the constraints.

<AttributeDef Name="Temperature">
	<Description>Temperature in K</Description>
	<Constraint>
		<IsBetween Min="0" Max="1e30"/>
		<Description>A temperature cannot be below absolute zero
and it never gets to 1e30 in Houston except on really hot
days.</Description>
	</Constraint>
</AttributeDef>

-----Original Message-----
Sent: Friday, October 02, 1998 4:10 PM
To: Arnold, Curt
Subject: RE: Questions on DCD




----------------------------------------
Dean Roddey
Software Weenie
IBM Center for Java Technology - Silicon Valley
roddey at us.ibm.com




Curt.Arnold at hyprotech.com on 10/02/98 12:18:44 PM
Please respond to Curt.Arnold at hyprotech.com
To: Dean Roddey/Cupertino/IBM at ibmus
cc:
Subject: RE: Questions on DCD


Instead of adding another parser, why wasn't the constraint specified as
XML.  i.e.

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