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Chapter 10: Modeling Conceptual Objects with Class Diagrams

Roughly, shows how relevant system concepts are structured and interrelated. Represented by UML class diagram . | Building System Models for RE Chapter 10 Modeling Conceptual Objects with Class Diagrams Building models for RE Chap.8: Goals Chap.9: Risks Chap.10: Conceptual objects Chap.11: Agents on what? why ? how ? who ? The object model Structural view of the system being modeled (as-is or to-be) Roughly, shows how relevant system concepts are structured and interrelated Represented by UML class diagram . “objects”, classes not in the OO design sense: RE is concerned with the problem world only ! classes with no operations: data encapsulation is a design concern; no design decisions here ! Multiple uses . precise definition of system concepts involved in other views, their structure & descriptive properties state variables manipulated in other views common vocabulary basis for generating a glossary of terms Modeling conceptual objects: outline What is a conceptual object? Entities Associations & multiplicities Attributes Specialization Aggregation More on class diagrams derived attributes, | Building System Models for RE Chapter 10 Modeling Conceptual Objects with Class Diagrams Building models for RE Chap.8: Goals Chap.9: Risks Chap.10: Conceptual objects Chap.11: Agents on what? why ? how ? who ? The object model Structural view of the system being modeled (as-is or to-be) Roughly, shows how relevant system concepts are structured and interrelated Represented by UML class diagram . “objects”, classes not in the OO design sense: RE is concerned with the problem world only ! classes with no operations: data encapsulation is a design concern; no design decisions here ! Multiple uses . precise definition of system concepts involved in other views, their structure & descriptive properties state variables manipulated in other views common vocabulary basis for generating a glossary of terms Modeling conceptual objects: outline What is a conceptual object? Entities Associations & multiplicities Attributes Specialization Aggregation More on class diagrams derived attributes, OR-associations, associations of associations Building object models: heuristic rules BookCopy Patron Loan BookCopy Patron Name Patron StudentPatron StaffPatron BookCopy Library What is a conceptual object? Set of instances of a system-specific concept . distinctly identifiable immutable, built-in identity e.g. 2 string instances “Justine Henin” are the same, but 2 Patron instances named Justine Henin are different can be enumerated in any system state in any state we can list all instances of the Patron concept currently involved in the system share similar features common name, definition, type, domain properties, common attributes, associations: see details later e.g. Email attrib of Patron; Loan assoc linking Patron and BookCopy may differ in their individual states and state transitions What is a state of an instance of conceptual object ? Tuple of functional pairs xi |® vi xi : object attribute, association vi : corresponding value for that instance E.g. instance tr of Train