Eight Steps to Crafting a Business Rule — Step 2: Determine Whether the Business Rule Already Exists
Last month, I talked about the first step in an eight-step approach for crafting a business rule. Once you have completed the first step of extracting the business rule, you're ready for the next step — determining whether the business rule already exists.
One of the basic principles of the business rules approach is to write a business rule only once. This means that, before you start crafting a business rule, you need to determine if someone else has already written it.
Although theoretically this makes sense, in practice, it takes discipline. It often seems easier to just write the rule from scratch rather than go to the trouble of searching for it; but it is invariably worth the effort.
- a central repository, or what Ron Ross calls a General RuleBook System (GRBS),
- consistent vocabulary.
General Rulebook System
Having all the rules in one place is enormously helpful. And, of course, a good General Rulebook System makes it easier to find existing business rules through various means (e.g., searching by term, by task, by product, etc.).
But even if you don't have a GRBS, at least try to have all the documents containing the business rules in one place (e.g., Business Requirement Documents (BRDs), Excel spreadsheets, Visio diagrams). These documents need to live on after projects are completed, so make sure they don't disappear into project archives and become inaccessible.
If you have a center of excellence, this group can be very helpful in pointing you to existing material. They may also know of other projects in flight that are working in the same business area and possibly touching on the same set of business rules.
You can also simply ask around — I know a lot of Business Analysts that keep their own copies of BRDs (etc.) so they can refer to them for subsequent projects.
There have been numerous articles on the importance of using consistent vocabulary in business rules. This is where the effort required to do that really pays off.
The reusability of the rules is much higher with consistent vocabulary simply because it is easier to find existing rules.
You may need to do some translations of the business vocabulary from the source material as the source material may not always be using the proper terminology. A concept model (also sometimes called a "fact model") is very helpful in narrowing down the terminology, especially if synonyms have been captured in the glossary. I generally find that it is helpful to keep a mapping of the terms in the source document to the terms in the concept model so that I can reference it as I write the rules.
At this stage, you will probably have a lot of questions on the terminology in the source material. To write business rules, the terminology needs to be very precise. The source material is usually less structured, and you'll often find different terms for the same thing.
Any questions on the terminology should be reviewed with your Subject Matter Experts. These discussions may lead to changes in the concept model, so make sure that whoever is responsible for maintaining the concept model either sits in on the discussions or is kept informed.
Searching for the Business Rules
When you're searching for the existing business rules, keep in mind that the existing rule might not be exactly the same but may overlap or may contain only some of the conditions. Searching by one or two terms allows you to get the broadest view.
If you do find existing rules, you need to understand the impact if you are making changes to the rule. Of course, if you are really organized and disciplined, you may already have done an impact analysis upfront and identified the business rules that are likely to be impacted. Even if you have, you should still check each rule.
Now that you have determined whether or not the business rule already exists, and possibly clarified some of the terminology, you are ready for the next step — determining whether the business rule computes or derives something. I'll deal with that next month.
Ronald G. Ross, "General Rulebook Systems (GRBS): What's the General Idea?" Business Rules Journal, Vol. 10, No. 7 (July 2009), URL: http://www.BRCommunity.com/a2009/b488.html
Rik Gerrits, "Putting Business Rules in the Hands of the Business," Business Rules Journal, Vol. 13, No. 4 (Apr. 2012), URL: http://www.BRCommunity.com/a2012/b645.html
Gladys S.W. Lam, "Top 10 Mistakes Business Analysts Make When Capturing Rules — Mistake #2: Not Focusing on Terminology," Business Rules Journal, Vol. 11, No. 12 (Dec. 2010), URL: http://www.BRCommunity.com/a2010/b568.html
Ronald G. Ross, "Concept Model vs. Fact Model vs. Conceptual Data Model — Just a Matter of Semantics?" Business Rules Journal, Vol. 13, No. 1 (Jan. 2012), URL: http://www.BRCommunity.com/a2012/b632.html
Ronald G. Ross, "What Are Fact Models and Why Do You Need Them (Part 1)," Business Rules Journal, Vol. 1, No. 5 (May 2000), URL: http://www.BRCommunity.com/a2000/b008a.html
Ronald G. Ross, "What Are Fact Models and Why Do You Need Them (Part 2)," Business Rules Journal, Vol. 1, No. 7 (July 2000), URL: http://www.BRCommunity.com/a2000/b008b.html
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, October 2011, 304 pp. URL: http://www.brsolutions.com/bbs
For more information on the RuleSpeak® technique, visit http://www.rulespeak.com
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