Definition of business rules

First we need to recognize that the Business Rules Forum (BRF) folks see rules as pretty big things.  Ron Ross talks about the possibility of 1000 or more rules in an ERP.  I think of those as analysis rules.  The more detailed implementation rules are also rules, but these don’t seem to hit the BRF radar.

To be clear,  I believe that the definition of a real rule is something like the following:

“If a junior HR employee opens an employee record for maintenance, he/she is allowed to change the address but not the salary field.”  Many folks from the rules community think that this is an implementation “thing” and not a rule at all.  I disagree.

But if that sort of thing is a rule, then a lot of the manifesto does not make sense and is not even true.

If you agree that the example above is a “rule,” then  there may be as many as 500,000 rules in a system and we need a very different way of thinking about them.

However, if you buy into my idea of analysis rules and implementation rules, then the manifesto is fine if you assume that it refers only to analysis rules.

Definitions:

• Analysis Rule: The rules that users “tell” you that are represented in the way in which users think and talk. For example, “Purchase orders over $50,000 need to go through three levels of approval.”  Analysis rules are vague and imprecise and are not directly implementable without further analysis.
• Implementation Rules: Rules that are complete enough to actually generate or drive a part of the system.  They should be readable and enterable by people, but are not expressed in natural language since natural language is not precise enough to be used for this purpose.  If it is precise enough, it is usually too wordy to be usable.  500,000 sentences are not manageable. An ERD is a rule representation for a subset of structural business rules.  It is precise enough to generate a data structure.  A process flow is also a suitable rule representation.  It can be read and manipulated by a user and can be made to be precise.

There is a lot more of this discussion in the BRIM white papers on the Dulcian web site.