It’s become more and more apparent that software vendors are misleading people (badly) about the true meaning of ‘business rule’. Time to set the record straight.
Here is an authoritative 3-part explanation. Take a moment and reacquaint yourself. As a business-oriented professional you’ll be glad you did!
|
Reference Sources
|
| [MWUD] |
Merriam-Webster Unabridged Dictionary (Version 2.5). [2000]. Merriam-Webster Inc. |
| [SBVR] |
Semantics of Business Vocabulary and Business Rules (SBVR) (Version 1.0). [January 2008]. Object Management Group. |
1. Rule
When we say rule we always mean real-world rule. Here’s the dictionary meaning of “rule”. That’s what we mean.
[MWUD ‘rule’ 1a]: guide for conduct or action;
[MWUD ‘rule’ 1f]: one of a set of usually official regulations by which an activity (as a sport) is governed [e.g.,] *the infield fly rule* *the rules of professional basketball* ;
[MWUD ‘criteria’ 2]: a standard on which a decision or judgment may be based
A real-world rule always tends to remove some degree of freedom. If it does not, it’s not a rule.
2. Under Business Jurisdiction
When we say business rule we mean only rules that the business can opt to change or to discard.
A business rule is always under business jurisdiction of your organization. The point with respect to external regulation and law is that your organization has a choice about how to interpret the regulations and laws for deployment into its day-to-day business activity – and even whether to follow them at all.
So external regulations are not business rules per se. Business rules include only the rules that a business creates in response to external regulation.
SBVR explains:
“The laws of physics may be relevant to a company … ; legislation and regulations may be imposed on it; external standards and best practices may be adopted.
These things are not business rules from the company’s perspective, since it does not have the authority to change them.
The company will decide how to react to laws and regulations, and will create business rules to ensure compliance with them. Similarly, it will create business rules to ensure that standards or best practices are implemented as intended.”
3. Business Rule
[SBVR]: a rule that is under business jurisdiction
A business rule is a criterion used to:
- guide day-to-day business activity
- shape operational business judgments, or
- make operational business decisions.
A number of years ago, a colleague of ours, Mark Myers, came up with a highly pragmatic test to determine whether some statement represents a business rule or a system rule. It almost always works.
Imagine you threw out all the systems running your business and did it all by hand (somehow). If you still need the statement, it’s a business rule. If you don’t, it’s not. A colleague on the SBVR standardization team, Don Baisley, puts it another way: “Business people don’t set variables and they don’t call functions.”
Some people think of business rules as loosely formed, very general requirements. Wrong. Business rules have definite form, and are very specific. Each should give well-formed, practicable guidance Here are a few simple examples expressed in RuleSpeak:
A customer that has ordered a product must have an assigned agent.
The sales tax for a purchase must be 6.25% if the purchase is made in Texas.
A customer may be considered preferred only if the customer has placed more than $10,000 worth of orders during the most recent calendar year.
Business rules represent a form of business communication and must make sense (communicate) to business people. If some statement doesn’t communicate, it’s not a business rule.
Consider this example: If ACT-BL LT 0 then set OD-Flag to ‘yes’. Not a business rule.
Consider another example: An account must be considered overdrawn if the account balance is less than $0. This statement communicates and therefore is a business rule.
More observations about business rules:
- In SBVR a business rule can be either a behavioral rule or a definitional rule.
- Business rules can be technical, but only in terms of the company’s know-how or specialized product/service, not in terms of IT designs or platforms.
- Expression of business rules should always be declarative, rather than procedural.
- A business rule statement should use terms and wordings about operational business things that should be based on a structured business vocabulary (concept model).
- Your company’s business rules need to be managed and single-sourced, so we strongly recommend rulebook management.
Business rules are not about mimicking intelligent behavior, they are about running a business.
Mimicking intelligent behavior in a generalized way is far harder (an order of magnitude or more) than capturing the business rules of an organization. Unfortunately, expert systems have generally focused on the former problem, causing considerable confusion among business practitioners.
~~~~~~~~~~~~~~~~~~~~
Excerpted from
Building Business Solutions: Business Analysis with Business Rules, by Ronald G. Ross with Gladys S.W. Lam,
An IIBA® Sponsored Handbook, Business Rule Solutions, LLC, 2011, 304 pp,
http://www.brsolutions.com/bbs
The standard Semantics of Business Vocabulary and Business Rules (SBVR)[1] offers fundamental insights about how to express business rules well. These common-sense insights can and should directly inform all expression of business rules – and any language that purports to support them. The first of these insights is the notion of practicable, which I discussed in my previous post. See: http://www.brsolutions.com/2015/06/29/practicable-insight-for-expressing-business-rules-well/
The second of these insights is the principle of wholeness. The descriptive text below is taken directly from SBVR itself.[2]Wholeness essentially means each business rule statement can be taken as fully trustworthy even in isolation from all other rules. The principle precludes priority schemes and rules that disable other rules, both of which can act to make any given rule less than fully trustworthy.
~~~~~~~~~~~~~~~~~~~
Principle: An element of guidance means only exactly what it says, so it must say everything it means.
Explanation: Each element of guidance must be self-contained; that is, no need to appeal to any other element(s) of guidance should ever arise in understanding the full meaning of a given element of guidance.
The full impact of an element of guidance for a body of shared guidance, of course, cannot be understood in isolation. For example, an element of guidance might be in conflict with another element of guidance, or act as an authorization in the body of shared guidance. The Wholeness Principle simply means that if a body of shared guidance is deemed free of conflicts, then with respect to guidance, the full meaning of each element of guidance does not require examination of any other element of guidance. In other words, each element of guidance can be taken at face value for whatever it says.
~~~~~~~~~~~~~~~~~~~~~~~~
www.BRSolutions.com
