Chapters Notes

Chapter 9:

Business Rules

© Karl E. Wiegers

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9.1 Classifying Business Rules

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 Facts - Simple truths - Associations and relationships often appear in data models

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 Constraints Restrictions on systems and users “Must,” “must not,” “may not,” “only,” “if”

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 Action enablers Conditions that trigger activities

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 Inferences Facts derived from other conditions

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 Computations Formulas, algorithms, tables

9.2 Discovering Business Rules

 Ask about rationale for process, constraints on process: ◦ Why must we do it that way? ◦ What does the government want? ◦ How is that calculated? ◦ What causes changes to objects? ◦ How does the system know what to do next? ◦ What can and cannot happen? (and why) ◦ What may the user do next? ◦ How are these pieces of data related?

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9.3 Documenting Business Rules

 Enterprise-wide catalog: ◦ ID (for easy reference) ◦ Definition ◦ Type ◦ Probability of change (static/dynamic) ◦ Source (company policy, public law, agency

regulation,…)

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