Rule Design Guidelines and Best Practices

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Using Business Rules – A Primer

Keshav DeshpandeSoftware Developerkdeshpande1@verizon.net

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• Application Architecture with Business Rules

• Separating Business Procedures from Business Rules

• Structure of a Business Rule

• Anatomy of Rule Execution

• Business Rule Modeling, Best Practices and Guidelines

• Business Rules vs Validation Checks

Topics

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Application Architecture with Business Rules

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Application Architecture with Business Rules

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Application Architecture with Business Rules

• Business procedure/workflow distinct from Business Rules

• Business Rules hosted and executed within rules engine

Implications Separation of concerns

• generally accepted as good application design pattern

Business rules can be independently modified• Modifications done outside of application code

Business Analysts can access/simulate/run/test Business Rules• in isolation from application

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Business Procedure Vs Business Rules

Example Business Procedure:

An incoming claim is routed to appropriate claim processor team, based on claim amount

Example Business Rule:

IF claim amount is greater than $10000

THENroute claim to Team A

Vs.

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Structure of a Business Rule

IF claim amount is greater than

$10000THEN

route claim to Team AA rule is a Declarative Expression comprising of –

ASSERTIONS and ACTIONS can have multiple ASSERTIONS (and-ed/or-ed

together)multiple ACTIONS (and-ed together)

Rules can be grouped together – expressed as DECISION TABLES or DECISION TREES

Assertion

Action

IF

THEN

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Anatomy of Rule Execution

A Rules Engine is a • ‘Fact-Assertion-Action’ engine (forward-chaining inference)• Container for rule execution

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Anatomy of Rule Execution

A Rules Engine is a • ‘Fact-Assertion-Action’ engine (forward-chaining inference)• Container for rule execution

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Business Rule Modeling

Mining Business Tier for Business Rules• Harvesting Business Rules – highly analytical, cross-

functional team undertaking

Segregate Business Procedures from Business Rules

A Business Rule exists to facilitate Business Operational Decisioning• imperative - frequent modifiability

Business Rules provide control and governance• “way-we-do-business”• influence behavior of business

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Business Rule Modeling

Frequently encountered question:

What about validation check “rules”?

Examples: • social security number validation• telephone number validation

Can I implement validation check routines as “business rules”?

You can, but should you?

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Business Rules Vs Validation Checks

Validation checks best NOT modeled as business rules If you absolutely have to - use the ‘frequency of modification’ as final

decision point

Business Rule Validation Check

• Strategic, ‘big picture’ connotation

• Business decision-oriented• Frequently modified• Modifications – consequence

of dynamic operational environment

• Influences “way-we-do-business”

• Tactical, narrow focus• Data-oriented• Not modified as frequently• Modifications are aspect of

data governance• Amount to pass/fail checks,

failures equate to errors

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Business Rule Modeling

Generally, these are NOT good Business Rules candidates:After all, why use a Rules Engine to execute –

Logic that is not likely to ever change, once implemented

Logic that does not have “way-we-do-business” connotations

Database lookups, data validation checks

Data transformations, long-running processes

Logic that has little influence over business operational behavior

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Thanks!

Please stay in touch at - kdeshpande1@verizon.net