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

• From: "Costello, Roger L." <costello@mitre.org>
• To: "'xml-dev@lists.xml.org'" <xml-dev@lists.xml.org>
• Date: Wed, 17 Jun 2009 07:55:13 -0400

Hi Frank,
 
> How about some more detail on how you're 
> defining "business rule"?

I shall try.

First an example of a business rule: 

    A Level 1 manager has a maximum signature
    authority of $10K.

Now a definition:

    Business rules are the foundational logic 
    that guides decisions and actions within 
    the business organization.

Thus, the above rule guides the business in deciding whether or not any given purchase request can be signed off by a Level 1 manager.

By externalizing the rules, and managing them, a business can quickly change its behavior. 

Rules can be analyzed for dependencies, consistency, and completeness. (A Business Rules Management System - BRMS - does this analysis automatically)

Contrast this with specifying the data to be exchanged among the parts of a system. There the emphasis is on vocabulary and structure, not on guiding decision making.

More examples of business rules:

    An auto loan applicant, living in Ohio, is
    underage if he/she is under 18 years of age.

    If a customer has no outstanding invoices, 
    then the customer is of preferred status.

It seems reasonable to me to use XML Schema and RELAX NG to specify the format of the data to be exchanged in a system, and use Schematron to express and manage the business rules. Keeping data and rules separate seems like a sensible business strategy.

What do you think?

/Roger

• Follow-Ups:
  • RE: Separate data from rules ... is the XML Schema 1.1 <assert> element a step backwards?
    • From: "Michael Kay" <mike@saxonica.com>

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