RE: [xml-dev] Are people really using Identity constraints specif ied in XML schema?

["Cox, Bruce" <Bruce.Cox@USPTO.GOV>]

DTD's (or Schemas, or CAM's, whatever) can't say everything that a
business has to say, but they can say it well enough to be recognizable
to the business folk, while being sufficiently well structured to
support the needs of developers.  No, not perfect, but readily improved
over the life of a project.  Isn't that what BCM is about (just reading
up on it between messages ... yes, it is Friday, even inside the
beltway).


Bruce B. Cox
SA4XMLT
+1-703-306-2606

-----Original Message-----
From: w3c@drrw.info [mailto:w3c@drrw.info] 
Sent: Friday, August 20, 2004 3:08 PM
To: Bullard, Claude L (Len)
Cc: Cox, Bruce; Thomas B. Passin; xml-dev@lists.xml.org
Subject: RE: [xml-dev] Are people really using Identity constraints
specif ied in XML schema?

Len,

Don't knock those XML DTDs.  You can only create small relatively simple
things with them - saves people from injurying themselves and others.  

Same reason why you cannot buy automatic assault weapons (but I have
mine back-ordered from Walmart for when the NRA manage to get that
repealed!)

It really must be Friday...

DW

Quoting "Bullard, Claude L (Len)" <len.bullard@intergraph.com>:

> You have a declarative system that can dynamically determine concepts 
> from contexts?  Or you have a pattern matcher?  Or you have a human 
> making maps?
> A registry is just another way to store apriori agreements plus a map.
> 
> Ummm... I have an RFP in front of me that requires we deliver a DTD.  
> Some subsumption is not yet complete.
> 
> len
> 
> 
> From: w3c@drrw.info [mailto:w3c@drrw.info]
> 
> Bruce,
> 
> Unfortunately schema was never intended to perform that role!
> 
> Not the least because it has no context driven mechanisms.
> 
> Apart from that - way too many people think it can do this 'magic' 
> because it has been over sold - well beyond the original requirements 
> the W3C started from.
> 
> We started off with a DTD - simple mission to describe the structure 
> permutations of an XML instance.  XSD then subsumed that role.  Snag 
> is neither is able to deliver fully.  It's all to easy to create an 
> XML instance, or set of instances, that look perfectly reasonable and 
> straightforward that is darn hard to then describe in schema.
> 
> I'm reminded of the situation in England in the 1500's - when Latin 
> was still the official legal language of law - but everyone uses 
> English as the working language. The solution beckons ; -)
> 
> DW.
> 
> Quoting "Cox, Bruce" <Bruce.Cox@USPTO.GOV>:
> 
> > In my world, attorneys speak "business rules" and IT folk speak 
> > "data constraints".  Often, their intention and extension are 
> > identical.  A really good schema is the membrane where these two 
> > sets touch each other, that is, it is equally successful from both
points of view.
> > 
> > 
> > Bruce B. Cox
> > SA4XMLT
> > +1-703-306-2606
> > 
> > -----Original Message-----
> > From: Thomas B. Passin [mailto:tpassin@comcast.net]
> > Sent: Thursday, August 19, 2004 4:59 PM
> > To: xml-dev@lists.xml.org
> > Subject: Re: [xml-dev] Are people really using Identity constraints 
> > specified in XML schema?
> > 
> > Roger L. Costello wrote:
> > 
> > > - The value of the <minimum-age> must be an integer.  This is a 
> > > constraint on the data.  It will not change over time.
> > 
> > Ha! What happens when the government decides that some relevant age 
> > is
> > 67.5 years instead of 67?
> > 
> > > Therefore, an XML Schema should simply constrain <minimum-age> to 
> > > be an integer.  Higher level applications should implement the 
> > > business rule that <minimum-age> be further constrained to 16.
> > > 
> > > How would you characterize the distinction between "business
rules" 
> > > and "constraints on data"?
> > 
> > A tricky, tricky issue - what is or is not a "business rule".  I 
> > suspect that in practice most constraints that are not business 
> > rules are in place for supposed programming reasons, or by force of
habit.
> > 
> > In one project I work on, we have a data type that is a union of 1) 
> > an enumeration of strings, 2) a string that follows a certain regex 
> > pattern, and 3) an integer constrained to a certain range.  No, 
> > don't bother to ask - it's one of those multi-agency
reconciliations.
> > 
> > --
> > Thomas B. Passin
> > Explorer's Guide to the Semantic Web (Manning Books) 
> > http://www.manning.com/catalog/view.php?book=passin
> > 
> > 
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> 
> 
> 
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