UML Diagrams A tool for presentation of Architecture

UML Diagrams A tool for presentation of Architecture

UML origins 80’s and early 90’s – explosion of modeling methods and notations Not to mention competition among methods people The “three amigos” (Booch, Jacobson, Rumbaugh) were working on the UML by 1996 OMG issued UML 1. 3 in March, 2000 OMG issued UML 2. 0 in July 2005

UML is Language n n Good for communication Standardization is essential Mostly graphical Example: used everywhere in Fowler NOT method n n You can use any design method you like to create UML diagrams Standardization can be helpful, but is not so important

More precise, less precise … Usefulness in design UML Natural language Code Precision

UML diagram types (1. x) Static diagrams n n Use case Class Dynamic diagrams n n n Object State Activity Collaboration (Called Communication in UML 2. 0) Sequence Implementation diagrams n n Component Deployment

UML 2. 0 New Diagrams Composite Structure – runtime decomposition of a class Interaction Overview – mixed sequence and activity Timing – interaction between object with timing Composite Structure – Runtime decomposition of class

Ron’s Belief: (Applied to UML) Use what makes sense Don’t be subservient to the tool You don’t always need electronic forms and editors – use paper and a pencil!

Use Case Diagram Elements Order Merchandise Order Book <<include>> Enter Credit Card consumer Check Order Status Use case names should be: Action-verb + object-phrase Remember: the ovals are use cases, NOT use case steps

Use Case Diagram

O-O Diagrams Class – static relationships n Inheritance, composition, association, dependency Object – dynamic snapshot n Object relationships at runtime, processes, threads

Classes Class name Attributes Operations Interface

Relationships dependency association generalization realization

Class Diagram

Stereotypes Text in << >> are stereotypes Stereotypes should be defined in the project’s glossary. Examples: <<interface>> Runnable + run( ) : void <<transfer object>> Bank. Message + account : long + balance : Money

Behavioral Diagrams Sequence n Interaction (for one use case) viewed by time Collaboration n Interaction (for one use case) viewed by structure State Chart n Internal state of an object (or class) across multiple use cases Activity n Interaction of multiple objects across multiple use cases (includes concurrent activity)

Sequence diagram

System Sequence diagram (a way to draw use case steps) : Customer : Amazon. com : credit. Card. Svc Add book to cart Confirm cart contents Request checkout Request authentication Provide credentials Present options Provide credit card info, shipping options Validate card Confirm order See Larman, Chpt 9 (2 nd edition)

Summing up UML is responsibility-oriented UML diagrams are a means to an end OOAD allows many benefits, but does not guarantee them

UML Usage Guide Use the diagrams to communicate Don’t become a slave to the diagrams What you leave out is as important as what you put into the diagram! Highlight important details; leave the rest out Rule of thumb: when in doubt, leave it out.

Review question Why are there so many types of diagrams?

Bonus material

Three levels of class diagrams Conceptual view n n Boxes are concepts, associations are associations : -) Concepts may or may not correspond to classes Specification view n n Boxes are interfaces Associations imply responsibilities Implementation view n n Boxes are classes Associations imply navigability Following Fowler, UML Distilled

Behavioral Things state message object Alice: Employee asynch message

Components and Nodes component node

System Packaging Component Diagrams n Modules and Packaging of software Deployment n n Physical Layout Hardware