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RE: Are people really using Identity constraints specif ied in

• To: "Cox, Bruce" <Bruce.Cox@U...>
• Subject: RE: Are people really using Identity constraints specif ied in XML schema?
• From: w3c@d...
• Date: Mon, 23 Aug 2004 22:39:12 -0400
• Cc: ""@winters.swishmail.com, "Thomas B. Passin" <tpassin@c...>, xml-dev@l...
• In-reply-to: <5DE01F898FC62747A4E16964244291B50334BD6D@E...>
• References: <5DE01F898FC62747A4E16964244291B50334BD6D@E...>
• User-agent: Internet Messaging Program (IMP) 3.2.2 / FreeBSD-4.8

Bruce,

A+ student!

And those bits that are way-complex - just become 'blackboxes' with an API from
the business layer anyway that is then parameter driven.

Once you have identified the key driven context parameters - those in any case
are going to direct - far more than lowlevel bit and byte decisions.  Eg. -
once I've decided what I'm buying and where I'm shipping it to - the payment
and shipping decisions are all then standard boilerplate.

DW.

Quoting "Cox, Bruce" <Bruce.Cox@U...>:

> 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@d... [mailto:w3c@d...] 
> Sent: Friday, August 20, 2004 3:08 PM
> To: Bullard, Claude L (Len)
> Cc: Cox, Bruce; Thomas B. Passin; xml-dev@l...
> Subject: RE:  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 repealed!)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@i...>:
> 
> > 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@d... [mailto:w3c@d...]
> > 
> > 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@U...>:
> > 
> > > 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@c...]
> > > Sent: Thursday, August 19, 2004 4:59 PM
> > > To: xml-dev@l...
> > > Subject: Re:  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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> 
> 
> 
> 
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  • RE: Are people really using Identity constraints specif ied in XML schema?
    • From: "Cox, Bruce" <Bruce.Cox@U...>

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