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RE: Separate data from rules ... is the XML Schema 1.1 <assert

• From: "Michael Kay" <mike@saxonica.com>
• To: "'Costello, Roger L.'" <costello@mitre.org>,<xml-dev@l...>
• Date: Mon, 15 Jun 2009 23:41:31 +0100

> 
> In the book Business Rules Applied, Barbara von Halle 
> presents the Business Rules Methodology, which fundamentally 
> is about separating rules from data:

If you're trying to deduce from that that it's desirable for the following
two constraints to be written in different places using different languages,
then I think that's pretty perverse:

(a) price and cost are both mandatory, margin is optional

(b) either price must be present, or cost and margin must both be present

I don't know von Halle's book, and I don't know how she defines her terms,
but in my view you can't create any kind of data model without using
business rules as your input, so if you try to take the business rules out
of the data model you are left with nothing.

Regards,

Michael Kay
http://www.saxonica.com/
http://twitter.com/michaelhkay 

• References:
  • Separate data from rules ... is the XML Schema 1.1 <assert> elementa step backwards?
    • From: "Costello, Roger L." <costello@mitre.org>