Rules that Give You Too Much Freedom
Freedom should be removed by rules. In fact, a rule that does not remove freedom in some way is not a rule according to the SBVR standard. That being said, you may be confused by the title of this column. Well, given this restriction on what a rule is and what you expect from a rule statement, there are still many ways to express such a rule.
RuleSpeak and SBVR's Structured English impose some restrictions on our use of language (see the box below), but due to the flexible nature of natural language you still have a lot of freedom ... consequently, we rarely see the same rule written in exactly the same way by different people using natural language.
There is a tendency to ask for a more restricted rule language to improve:
- consistency in writing similar rules by different people,
- consistent interpretation (non-ambiguity),
- support for validation & verification,
- translation to software systems.
| RuleSpeak and SBVR restrictions
Every business rule statement must contain at least one business rule keyword.
The keywords in RuleSpeak are:
The keywords in SBVR Structured English are:
Expressing rules as decision tables or decision trees greatly reduces your freedom of form but also your expressiveness. So, when I need the expressiveness of natural language, I introduce very specific rule patterns to restrict my freedom and gain rigor.
- ... must be calculated as ....
- A ... for ... must be calculated as ....
- A <data element> for a <timeframe> and a <location> must be calculated as <formula>.
Each pattern is more specific, provides more guidance, and (consequently) less freedom. The last pattern above is even specific to a particular domain.
Sentence patterns seem to be the fashion today. They are not only popular for rules but also used in the descriptions of user stories in agile projects: As a <role> I want <something> so that <benefit>.
Rules must decrease freedom and so must rule sentence patterns. I am curious about the sentence patterns you use or recognize in your organization. Please send me an e-mail with your examples at email@example.com .
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BRSolutions Professional Training Suite
All About Concepts, Policies, Rules, Decisions & Requirements
We want to share some insights with you that will positively rock your world. They will absolutely change the way you think and go about your work. We would like to give you high-leverage opportunities to add value to your initiatives, and give you innovative new techniques for developing great business solutions.
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