Object-Oriented Analysis and Design
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Events and Use Cases
Use case Activity the system carries out Entry point into the modeling process
Event decomposition: help identify use cases
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
Looking At Each Event and the Resulting Use Case
Enter use cases in an event table
Event table includes rows and columns Each row is a record linking an event to a use case
Columns represent key information
Problem Domain Classes
Problem domain Set of work-related “things” in system component 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
Types of Things
Things can be identified with methodology
Separate the tangible from the intangible
Include information from all types of users
Ask important questions about nature of event “What actions upon things should be acknowledged and recorded by the
system?”
Example case: customer placing an order
Procedure for Developing an Initial List of Things
List nouns users 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
Attributes of Things
Specific details of things are called attributes
Analyst should identify attributes of things
Identifier (key): attribute uniquely identifying thing Examples: Social Security number, vehicle ID number, or product ID
number
Classes and Objects
Domain model class diagram as UML class OOA applies domain model class diagram to things
Problem domain objects have attributes Software objects encapsulate attributes and behaviors
Behavior: action that the object processes itself
Software objects communicate with messages Information system is a set of interacting objects
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
Associations among Things
Analyst document entity associations ( relationships) Example: “Is placed by” and “works in”
Associations apply in two directions Customer places an order An order is placed by a customer
Multiplicity: the number of associations One to one or one to many
Next Tonight
Review any Requirements Documents that have been produced
Prep for next week’s interview with Sponsor
Next Week Sponsor Interview
6:30 – 7:30p: Degree and Certificate Auditor
7:30 – 8:30p: Baseball League Information Manager
Have Sponsor Review your Inception Phase documents
Ask Sponsor questions necessary to have detail to create Event Table, Activity Diagrams, and Domain Model Class Diagrams