SEG4110 – Advanced Software Design and Reengineering

TOPIC A

Review of UML

SEG4110 - Topic A- Review of UML 2

What is UML?

The Unified Modelling Language is a standard graphical language for modelling object oriented software

• Developed when Booch, Rumbagh and Jacobson merged their approaches.

• In 1997 the Object Management Group (OMG) started the process of UML standardization

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Reminder about Naming classes

• Use capital letters—E.g. BankAccount not bankAccount

• Use singular nouns

• Use the right level of generality—E.g. Municipality, not City

• Make sure the name has only one meaning—E.g. ‘bus’ has several meanings

SEG4110 - Topic C - Advanced UML and Umple 4

Umple

A technology for programming in UML

• Model-Oriented Programming

Adds associations and attributes to programming languages

•Java

•PHP

•Ruby

Stand alone code-generator is online at

•http://cruise.site.uottawa.ca/umpleonline/index.php

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Declaration of classes and attributes in Umple

class Student

{

studentNumber; // defaults to String

String grade;

Integer entryAverage; // implemented as int

}

Open in UmpleOnline

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Associationsclass Student { id; name; }

class Course { description; code; }

class CourseSection {

sectionLetter;

1..* -- 1 Course;

}

association {

* CourseSection;

* Student registrant;

}

Open the above in UmpleOnline

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Selected patterns

class University {

singleton;

String name;

}

Open the above in UmpleOnline

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Reminder about Labelling associations

• Each association can be labelled, to make explicit the nature of the association

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Analyzing and validating associations 1

• Many-to-one

—A company has many employees,

—An employee can only work for one company.- This company will not store data about the moonlighting

activities of employees!

—A company can have zero employees- E.g. a ‘shell’ company

—It is not possible to be an employee unless you work for a company

*worksForEmployee Company1

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Analyzing and validating associations 2

• Many-to-many

—A secretary can work for many managers

—A manager can have many secretaries

—Secretaries can work in pools

—Managers can have a group of secretaries

—Some managers might have zero secretaries.

—Is it possible for a secretary to have, perhaps temporarily, zero managers?

*

supervisor

*****1..*Assistant Manager

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Analyzing and validating associations 3

• One-to-one

—For each company, there is exactly one board of directors

—A board is the board of only one company

—A company must always have a board

—A board must always be of some company

11

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Analyzing and validating associations

Avoid unnecessary one-to-one associations

Avoid this do this

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Association classes

• Sometimes, an attribute that concerns two associated classes cannot be placed in either of the classes

• The following are equivalent

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Reflexive associations

• It is possible for an association to connect a class to itself

class Course

{

* prerequisite -- * Course successor;

* self multuallyExclusive;

}

Open in Umple (the symmetric reflexive association doesn’t show graphically yet)

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Directionality in associations

• Associations are by default bi-directional

• It is possible to limit the direction of an association by adding an arrow at one end

• Open in Umple

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Object Diagrams

• A link is an instance of an association

—In the same way that we say an object is an instance of a class

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Inheritance and the Isa Rule

Inheritance• The implicit possession by all subclasses of features

defined in its superclasses

Always check generalizations to ensure they obey the isa rule

• “A checking account is an account”• “A village is a municipality”

Should ‘Province’ be a subclass of ‘Country’?• No, it violates the isa rule

—“A province is a country” is invalid!

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Inheritance, Polymorphism and Variables

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Avoiding unnecessarygeneralizations

rockbluesclassicaljazzmusic video

video audio

subcategory subcategorysubcategorysubcategorysubcategory

:RecordingCategory :RecordingCategory

:RecordingCategory :RecordingCategory :RecordingCategory :RecordingCategory:RecordingCategory

9th Symphony

:Recording

Let it be

:Recording

The BeatlesBeethoven

Inappropriate hierarchy ofclasses, which should beinstances

Improved class diagram,with its correspondinginstance diagram

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Avoiding having instances change class

• An instance should never need to change class

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• A composition is a strong kind of aggregation

—if the aggregate is destroyed, then the parts are destroyed as well

Composition

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Interfaces

An interface describes a portion of the visible behaviour of a set of objects.

• An interface is similar to a class, except it lacks instance variables and implemented methods

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OCL – More to come in a later lecture

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Use Case Diagrams

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Example of generalization, extension and inclusion

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Example Description of a Use Case

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Sequence diagrams – an example

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• An iteration over objects is indicated by an asterisk preceding the message name

Sequence Diagrams – an example with replicated messages

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• If an object’s life ends, this is shown with an X at the end of the lifeline

Sequence Diagrams – an example with object deletion

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State Diagrams – an Example of Transitions with Time-outs and Conditions

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State Diagrams – Example with Conditional Transitions - CourseSection class

requestToRegister (aStudent)/createRegistration

ClosedclassSize >= maximum

cancel

openRegistration

Planned

OpenEnoughStudents

OpenNotEnoughStudents

classSize >= minimum

requestToRegister (aStudent)/createRegistration

closeRegistration

closeRegistration

cancel

Cancelled

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State Diagram – An Example with Substates CourseSection Class Again

Open the previous page and this one in Umple

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Activity Diagrams – An Example –Course Registration

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Package Diagrams

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Example of Multi-Layer Systems

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Component Diagrams

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An Example of a Distributed System

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Example of a Broker System

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Example of a Pipe-and-Filter System -Sound Processing

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Example of the MVC Architecture for a User Interface

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Example of the Service-Oriented Architecture

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Abstraction-Occurrence

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Abstraction-Occurrence

Square variant

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General Hierarchy

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Player-Role

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Singleton

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Observer

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Delegation

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Façade

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Proxy

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Deployment Diagrams