Events and Use Cases

2. Events and Use Cases • Use case • Activity the system carries out • Entry point into the modeling process • Elementary business processes (EBPs) • Basic unit of analysis • Initiated by event occurring at specific time and place • Discrete system response that adds business value Object-Oriented Analysis and Design with the Unified Process

3. Figure 5-1 Identifying Use Cases by Focusing on Users and their Goals Object-Oriented Analysis and Design with the Unified Process

4. Event Decomposition • Event decomposition • Develops use cases based on system response to events • Perceives system as black box interfacing with external environment • Keeps focus on EBPs and business requirements • Result of the decomposition: • List of use cases triggered by business events • Use cases at the right level of analysis Object-Oriented Analysis and Design with the Unified Process

5. Types of Events • External Events • Occur outside the system • Usually caused by external agent • Temporal Events • Occurs when system reaches a point (deadline) in time • State Events • Asynchronous events responding to system trigger Object-Oriented Analysis and Design with the Unified Process

6. Figure 5-3 External Event Checklist Object-Oriented Analysis and Design with the Unified Process

7. Figure 5-4 Temporal Event Checklist Object-Oriented Analysis and Design with the Unified Process

8. Figure 5-7 Events Deferred until Later Iterations Object-Oriented Analysis and Design with the Unified Process

9. Figure 5-10 Information about each Event and the Resulting Use Case in an Event Table Object-Oriented Analysis and Design with the Unified Process

10. Problem Domain Classes • Problem domain • Set of work-related “things” in system component • Things have data representation within system • Examples: products, orders, invoices, customers • OO approach to things in problem domain • Objects that interact in the system • Identify and understand things in problem domain • Key initial steps in defining requirements Object-Oriented Analysis and Design with the Unified Process

11. Figure 5-12 Types of Things Object-Oriented Analysis and Design with the Unified Process

12. Developing an Initial List of Things • List nounsusers mention when discussing system • Event table as source of potential things • Use cases, external agents, triggers, response • Select nouns with questions concerning relevance • Further research may be needed Object-Oriented Analysis and Design with the Unified Process

13. Figure 5-14 Associations Naturally Occur between Things Object-Oriented Analysis and Design with the Unified Process

14. Attributes of Things • Specific details of things are called attributes • Attributes – sound familiar? • Analyst should identify attributes of things • Identifier (key): attribute uniquely identifying thing • Examples: Social Security #, vehicle ID #, or product ID # • Compound attribute is a set of related attributes • Example: multiple names for the same customer Object-Oriented Analysis and Design with the Unified Process

15. Domain Model Class Diagram Notation • Class diagram key • General class symbol: rectangle with three sections • Sections convey name, attributes, and behaviors • Methods (behaviors) not shown in domain model class diagram • Lines connecting rectangles show associations • Multiplicity reflected above connecting lines • Domain class objects reflect business concern, policies, and constraints Object-Oriented Analysis and Design with the Unified Process

16. Figure 5-21 An Expanded Domain Model Class Diagram Showing Attributes Object-Oriented Analysis and Design with the Unified Process

17. Figure 5-25 A Generalization/Specialization Hierarchy Notation for Motor Vehicles Object-Oriented Analysis and Design with the Unified Process