Notes

Outline

Introduction to UML II Jagdish Gangolly State University of New York at Albany

Introduction to UML II Classes Relationships Class Diagrams Advanced Classes: Classifiers Advanced Relationships Interfaces, Types & Roles

Classes I    A Class is a set of objects that share the same attributes, relationships, operations, and semantics. Class Name (unique, textual string, prefixed by package name to give pathname) Attribute (named property of the class, takes values from a specified domain) Relationships * Operations/Methods (implementation of a service requested by any object of the class to affect behavior) Responsibility (contract or obligation of a class)

Classes II    Specification of all the details in classes provides much of the vocabulary of the application domain. STEPS: Identify things users/implementors use to describe the problem or solution in the domain in order to find abstractions For each abstraction, identify set of responsibilities (class definition must be clear; responsibilities must be balanced between classes) Provide attributes and operations needed to carry out the responsibilities

Class Diagrams I Class diagrams are used to: model the vocabulary of the system model simple collaborations Model database schema

Class Diagrams II: Vocabulary Identification of abstractions in the application domain (described earlier) Need for examination of documents in the domain Examination of text in the domain

Class Diagrams II: Collaborations Identification of collaborations Identification of classes interfaces and other collaborations participating Identification of relationships in the collaboration Use of scenarios to walk through the things in collaborations

Class Diagrams II: Database Schema Identification of classes in the model that transcend application Creation of class diagram containing such persistent classes Expanding the structural details of the classes and the cardinalities of associations Simplification of the logical structure by introducing intermediate abstractions Business rules on the manipulation of sets of objects must be encapsulated in a higher layer

Relationships I Dependencies (using relationships: using another class as an argument in the signature of an operation) Generalisation (A-KIND-OF relationship) Association (structural relationship)

Relationships II: Concepts Name Role Multiplicity Zero-or-one:  0 .. 1 Exactly one: 1 One-or-more: 1 .. * Many: 0 .. * Inheritance (Single & Multiple) Aggregation (whole/part, IS-PART_OF)

Advanced Classes & Relationships Visibility Public (+) Private  (-) Protected  (#) Scope Instance Classifier Abstract class (name in italics, Fig 9-5, p.126) Root & Leaf classes ({root}, {leaf}) Polymorphic operations