Chapter 9 Domain Models The classic OOAD model

Chapter 9 Domain Models The classic OOAD model

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Domain Model • Representation of real-situation conceptual classes • Not software objects! • Model: – Domain objects (conceptual classes) – Associations – Attributes of conceptual classes

Things not in a Domain Model • Software artifacts • Responsibilities or methods • Data Model

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Why? • Understand key concepts of domain – Key concepts – Vocabulary • Lower the gap between representations

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How? • Reuse an existing model – Easier – Less error prone – Many problems are not new • Category list – Text has a table of common categories (table 9. 1) • Noun phrases – Use with care!

Examples using concept list • Fig 9. 7 is POS domain • Fig 9. 8 is Monopoly

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Guidelines • • • Report objects Think like a mapmaker Modeling the unreal world Attributes vs. classes Description classes

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Associations • Things that need to be remembered • Use with care • May or may not be implemented in software • Naming: – class. Name-verb. Phrase-class. Name

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Attributes • Information that needs to be remembered

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Datatypes • Use simple types • Define complex types where needed – Subparts – Needs operations – Has attributes (e. g. start date) – Units – Polymorphic types

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Summary – Domain Models • A domain model is used to understand the domain • It is an artifact that is developed iteratively in Agile