Together and UML Greg Johnson CSE 230 – Software Engineering Spring 2007

New Project Dialog

Use-Case Diagram A use-case is a set of scenarios tied together by a common user goal A scenario is a sequence of steps describing an interaction between the user and the system

Use-Case Example Web-based store purchase –Shop online Browse catalog Add items to shopping cart –Checkout Provide shipping information Provide credit card information Confirm the sale –System checks authorization and confirms the sale immediately and via

Use-Case Example Another scenario would be if the credit card authorization fails Use-Case would be “Buy a Product” with successful purchase and authorization failure as two scenarios

Use-Case Diagram

Class Diagrams Describes the types of objects in the system Describes the static relationships between the objects –Associations – (e.g. a customer may purchase several books) –Subtypes – (e.g. a biography is a non-fiction book) Class diagrams show the attributes and operations of a class

Adding a Class Click on class button and then on an empty area of the diagram grid

Adding to a Class Add an attribute –CTRL + A –Right-click menu Add an operation –CTRL + O –Right-click menu

Access Privileges + Public Access - Private Access # Protected Access

Perspectives Conceptual Specification Implementation

Conceptual Perspective The diagram is intended to represent the concepts in the application domain Naturally, there is a relationship from concepts to the classes that implement them, but often there is no direct mapping Drawn with little to no regard to the software that will implement user requirements in this domain Should be largely language-independent

Specification Perspective Consider interfaces of the software, not implementation OO design places emphasis on the difference between interface and implementation

Implementation Perspective Classes exist and interfaces have been specified “laying the implementation bare” This perspective is most often used, but Specification Perspective is often a better one to take

Which Perspective? Draw conceptual models for analysis Draw specification models when working with software Draw implementation models only to illustrate an implementation technique

Less is More Don’t try to model everything Stick to a core set of key areas Better to have a few diagrams that are used and kept up-to-date than have many obsolete models

References Fowler, Martin. UML Distilled. Addison Wesley Longman