The BRS Rule Classification Scheme

In my May column^[1] this year, I wrote about the BRS RuleSpeak^TM sentence templates^[2] for expressing rules in structured English.  These templates are based directly on a fundamental classification scheme for rules that had to be worked out beforehand.

I have written about that scheme a number of times over the past decade, including in both my books on business rules.  However, we have recently received a number of inquiries about it -- I guess the interest in classifying rules is picking up -- so in response, I will present it here in compact form, with examples.

The BRS Rule Classification Scheme reflects how rules react to events.  A given rule can react in one of only three possible ways to an event -- hence there are three fundamental categories of rules in the scheme.

These three categories, which are defined in the table below, are intrinsic, definitive, and mutually-exclusive.  For that reason, they provide a sound foundation for the comprehensive set of sentence templates in RuleSpeak^TM.  They also have well-defined subcategories, as the table also indicates.  These provide an even richer basis for organizing the sentence templates -- as well as for gaining a much better understanding of your company's rules.

Category/Subcategory	Common Name	Definition
1.0 Rejector	Constraint	Any rule that tends to disallow ("reject") an event if a violation of the rule would result.   Rejectors are constraints that shield the business from incorrect data (or state) -- that is, from information that violates Business Rules. For example, a Rejector might be specified to prevent a customer from placing an order on credit if the customer has a poor payment history. Sample Rule Statements using RuleSpeakTM Using the "Must" Template Rule:   A purchase order taken during a snowstorm must be approved by at least two managers. Using the"May ... Only if" Template Rule:   A withdrawal for an account may be made only if the account is active. Using the "May ... Not" Template Rule:   An order may not be shipped if the outstanding balance of the customer's account exceeds the customer's credit authorization. Using the "May ... No" Template Rule: A territory may include no more than one of the following: Non-candidate traditional gas station. Ultra-service. Food outlet.
2.0 Producer		Any rule that neither rejects or projects events, but rather simply measures or computes, or derives or infers, automatically. Producers are categorized as either Computation Rules or Derivation Rules.
2.1 Computation Rule	--	Any Producer-type rule that computes a value automatically, following standard mathematical operations (e.g., SUM, MULTIPLY, AVERAGE, etc.) specified explicitly. For example, a Computation Rule might be given to compute customer's "annual order volume." Sample Rule Statement using RuleSpeakTM Rule:   A product's cost must be computed as the sum of the cost of all its components.
2.2 Derivation Rule	Inference Rule	Any Producer-type rule that infers (a derived term or fact) automatically based on conditions specified explicitly. For example, a Derivation Rule might be given to indicate whether a person is considered a woman, based on that person's age and gender. Sample Rule Statement using RuleSpeakTM Rule:   A customer must be considered high-risk, if the outstanding balance exceeds $1,000 on each of their last three successive invoices.
3.0 Projector	Stimulus/ Response Rule	Any rule that tends to take some action automatically when a relevant event occurs. Such an action might be to create or delete data, enable or disable another rule, set some value, execute some program or procedure, etc.   A Projector thus does not reject events (as Rejectors do), but rather, automatically projects them -- that is, causes some new event(s) as a result of them. Projectors generally prescribe automatic system behavior, providing a productivity boost for workers. For example, a Projector might be specified to reorder stock automatically if the quantity on hand drops below a certain point.
3.1 Enabler	--	Any Projector-type rule that has one of the following effects: Create or delete instances of data. Switch instances of a rule "on" or "off." Allow or disallow executions of an process or procedure. Sample Rule Statements using RuleSpeakTM Subject is "Data" Rule:   Outstanding issues must be deleted, when a case is closed. Subject is a Rule ("Exception-Type Rules") Rule:   The one-borrower-per-library-card rule must not be enforced, if one of the borrowers that holds the library card is 'Bill Gates.' Subject is a Process or Procedure Rule:   Send-appointment-notice must be disabled, if client's-address is unknown.
3.2 Copier	--	Any Projector-type rule that sets the actual value(s) of a data type. Such data type may be complex, and need not necessarily be stored (persistent). For example, a Copier might be used to initialize the tuition owed by a student in a given semester to the base tuition for that semester when the student enrolls. Sample Rule Statements using RuleSpeakTM Subject Refers to "Stored" Data ("Initialization Rules") Rule:   Applicable-sales-tax must be set to '8.25%,' if order-fulfillment-date = '2001.' Subject Refers to "Output" Data ("Presentation Rules") Rule:   An order must be displayed to the screen in red, if the order is overdue.
3.3 Executive	Trigger	Any Projector-type rule that causes a process or procedure to execute, or a rule to fire. Sample Rule Statements using RuleSpeakTM Subject is a Process or Procedure Rule:   Send-advance-notice must be executed for an order, when the order is shipped. Subject is a Rule Rule:   The projected-shipment-date-rule must be fired, when a shipment is displayed to the screen.

References

[1]  Ronald G. Ross, "RuleSpeak^TM -- Templates and Guidelines for Business Rules," Business Rules Journal, Vol. 2, Nbr. 5 (May 2001), at: www.BRCommunity.com/a2001/b066.html.

[2]  Refer to "RuleSpeak^TM Sentence Templates: Developing Rule Statements Using Sentence Patterns" in the BRS RuleSpeak^TM Practitioner Kit.   The Kit provides extensive guidance and additional examples, and is available for free download, at www.BRSolutions.com/rulespeak_download.shtml.