--- title: "Identify conceptual classes; create domain model" subject: "Object Oriented Analysis and Design" chapter: 2 key: "semester_6/object_oriented_analysis_and_design:conceptual-classes-domain-model-steps" source: https://www.bctengineer.com/q/semester_6/object_oriented_analysis_and_design/conceptual-classes-domain-model-steps site: BCT Engineering --- # Identify conceptual classes; create domain model Object Oriented Analysis and Design · Chapter 2: Object Oriented Analysis - Asked in: 2073 Bhadra, 6 marks - Video: [Domain model, Conceptual class & Description class](https://www.youtube.com/watch?v=UYICQcMz8EM) — Revathi Prakash - Answer checked by Claude Sonnet 5.5 on 2026-10-14 - Page: https://www.bctengineer.com/q/semester_6/object_oriented_analysis_and_design/conceptual-classes-domain-model-steps - Whole chapter: https://www.bctengineer.com/md/semester_6/object_oriented_analysis_and_design/chapter-2 ## Question Describe the strategies to identify conceptual classes. Describe the steps to create a Domain Model used for representing conceptual classes. ## Short answer Strategies include a category checklist for concepts like transactions, roles, and physical items, noun phrase identification from use cases, and reusing existing models. Steps: list candidate classes, draw them in a diagram, add associations and attributes, then refine with generalization and review the model. ## Answer A **conceptual class** is an idea, thing or object of the real problem domain (not a software class) that is important to the system, described by its symbol (name), intension (definition) and extension (set of examples). #### Strategies to identify conceptual classes 1. **Use a conceptual class category list.** Check categories such as: physical or tangible objects (Register, Airplane), specifications/descriptions (ProductDescription), places (Store), transactions (Sale, Payment, Reservation), transaction line items (SalesLineItem), roles of people (Cashier, Customer), containers (Store, Bin), things in a container (Item), computer/electromechanical systems (CreditCardAuthorizationSystem), abstract noun concepts (Hunger), organisations (SalesDepartment), events (Sale, Meeting), processes, rules and policies, catalogs, financial records, manuals and books. 2. **Noun phrase identification.** Take the nouns and noun phrases from the use case text (fully dressed description) as candidate classes or attributes. Care is needed since language is ambiguous and some nouns are attributes or synonyms. 3. **Reuse or modify existing models** of the domain from books and standards. Guidelines: it is better to over-specify than miss concepts; do not exclude a class because it has no attributes; a doubtful concept may be modelled as an attribute only if it is plain data (text/number). #### Steps to create a domain model 1. **List candidate conceptual classes** using the strategies above for the current use cases. 2. **Draw them** in a class diagram (rectangles with names only, no operations). 3. **Add associations** needed to satisfy the information requirements (name, multiplicity, role). 4. **Add attributes** that must be remembered (simple data types). 5. **Refine:** add generalisation, remove synonyms and redundant ones, add aggregation if useful, specification classes (e.g. `ProductDescription`). 6. **Review** the model against the use cases and with the domain experts; iterate. ```text +-------+ 1 * +------+ 1 1..* +----------+ * 1 +---------+ | Store |-------| Sale |---------| SalesLine|-----| Product | +-------+ +------+ +----------+ | Descr. | | 1 +---------+ | 1 +---------+ | Payment | +---------+ ``` ## Check yourself The answer's key points as multiple-choice questions, with the correct option and why. 1. How is a conceptual class described? A. By its methods and code B. By its table and index C. By its screen and button D. By its symbol (name), intension (definition) and extension (examples) Answer: D. A conceptual class is an idea of the real domain described by symbol, intension and extension. (Key point: Conceptual class description) 2. What is the noun phrase strategy? A. Take nouns and noun phrases from use case text as candidate classes or attributes B. Take verbs as classes C. Copy class names from code D. Use only adjectives Answer: A. Nouns from fully dressed use cases are candidates; care is needed since some are attributes or synonyms. (Key point: Noun phrase identification) 3. Which is a category in the conceptual class category list? A. Compiler flags B. Source files C. Transactions such as Sale, Payment, Reservation D. Network cables Answer: C. The list includes transactions, physical objects, roles of people, places, events, catalogs and more. (Key point: Category list strategy) 4. Which is the correct order of steps? A. Add attributes, then list classes, then review B. Draw, then list, then review, then add associations C. List candidate classes, draw them, add associations, add attributes, refine, review D. Review first, then list classes Answer: C. Steps: list candidates, draw, add associations, add attributes, refine, and review against use cases. (Key point: Steps of domain model creation) ## Related in Object Oriented Analysis and Design - [Conceptual, specification, implementation model classification](https://www.bctengineer.com/question.md?key=semester_6%2Fobject_oriented_analysis_and_design%3Ahospital-conceptual-specification-implementation) — Object Oriented Analysis and Design, chapter 2 - [Create classes from design class diagrams](https://www.bctengineer.com/question.md?key=semester_6%2Fobject_oriented_analysis_and_design%3Aclasses-from-design-class-diagram) — Object Oriented Analysis and Design, chapter 4, asked 2× - [Buy a Product conceptual model](https://www.bctengineer.com/question.md?key=semester_6%2Fobject_oriented_analysis_and_design%3Aonline-store-conceptual-model) — Object Oriented Analysis and Design, chapter 2 - [Domain modeling; attributes and associations guidelines](https://www.bctengineer.com/question.md?key=semester_6%2Fobject_oriented_analysis_and_design%3Adomain-modeling-attributes-associations) — Object Oriented Analysis and Design, chapter 2 - [Constraint specifications in bank account model](https://www.bctengineer.com/question.md?key=semester_6%2Fobject_oriented_analysis_and_design%3Aconstraint-specification-bank-account-model) — Object Oriented Analysis and Design, chapter 2 ## Related in other subjects - [Model building, verification, validation steps](https://www.bctengineer.com/question.md?key=semester_8%2Fsimulation_and_modeling%3Amodel-building-verification-validation) — Simulation and Modeling, chapter 7 - [Conceptual design of IS](https://www.bctengineer.com/question.md?key=semester_8%2Finformation_system%3Aconceptual-design-steps) — Information System, chapter 5 - [Conceptual dependency and primitives](https://www.bctengineer.com/question.md?key=semester_6%2Fartificial_intelligence%3Aconceptual-dependency-primitives) — Artificial Intelligence, chapter 5 - [Frequency reuse and channel assignment strategies](https://www.bctengineer.com/question.md?key=semester_7%2Fwireless_communication%3Afrequency-reuse-channel-assignment) — Wireless Communication, chapter 2