Computer Science for Engineers - KIT · software development process • UML is not a method, but rather a notation (description technique) • UML is independent from the developing

Computer Science for Engineers

Lecture 4Object Orientation – part 2

Prof. Dr. Dr.-Ing. Jivka OvtcharovaDipl. Wi.-Ing. Dan Gutu

20th of November 2009

Prof. Dr. Dr.-Ing. Jivka Ovtcharova – CSE-Lecture – Ch. 3 - WS 09/10 - Slide 2

Outline

Lecture Content

3. Object orientation

3.2. Object-oriented modelling with UML

3.3.2. Use Case models

3.2.3. Static models

3.2.4. Dynamic models

3.3. Methods of the OO Analysis and Design

1. Preface

3.1.1. Introduction

3.1.2. Objects and classes

3.1. Introduction and basic concepts

3.1.3. Attributes of object orientation

3.2.1. Intro

3.2.5. Summary

2. Basics


What is UML?

• UML stands for „Unified Modeling Language“

• The standardization of UML occurs through the OMG (Object Management Group) www.omg.org

• UML integrates almost all techniques up till now with

- Data modeling (Entity Relationship Diagrams)

- Descriptions of workflows and object behavior

- Structure implementation

• The visualization with UML supports the entire software development process

• UML is not a method, but rather a notation (description technique)

• UML is independent from the developing environment (languages, operating system, etc.)3.

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http://www.omg.org/


What is UML not?

• Not a programming language (advantageous for the modeling of complex circumstances)

• Not redundant free; often multiple representation or style possibilities: sequence and collaboration diagrams,

• Not a process description, no procedure model (even when it appears so)

• No automated tools or tool descriptions

• UML diagrams are limited in what they can express. Not everything can be represented with UML

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Diagrams in UML

• UML shows the problem from multiple perspectives. Repetition of each aspect in the form of a definite diagram.

(example: the design of a house, which is comprised of a floor plan, outline, lateral view, etc.)

- Each of these diagrams has a special application area for which it was purposely designed.

• The diagrams contain different graphical elements- The meaning of the element (semantic) is exactly determined and in all diagram

forms the same.

• The UML can be very complex due to the many diagrams, but strongly represents the problem to be solved.

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Diagram types in UML

• Use-Case-Model- Abstract description of the collaboration of actors with a system. Also

sometimes called a black-box system.

• Static Model- Class and instance diagrams: the most important diagram type of UML.

• Dynamic Model- Activity diagram: shows the progression of activities

- Interaction diagrams: graphical representation of a scenario(with emphasis on a timely progression)

- Condition diagram: shows the progression of conditions

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Diagramtype Diagram Phase Application area

Use case diagrams

•Requirements•Definition •Creation•Delivery

Business processes, general applications

Static Models

Class diagramsInstance diagrams

•Definition •Creation

Everywhere, the class diagram is the mostImportant diagram in UML

Interactiondiagrams

Shows the information flow and the time flow of the cooperation of the objects

Dynamic Models

Collaborationdiagrams

Timeflow structure with few messages

Sequence-diagrams

Timeflow structure with few classes

State diagramsRepresentation of the dynamic behavior

Use cases



Diagram types and application areas


Outline

Lecture Content







1. Preface

3.1.1. Introduction




3.2.1. Intro

3.2.5. Summary

2. Basics



Use case diagrams



Static Models




Interactiondiagrams


Dynamic Models



Sequence-diagrams



Use cases





Use Case Model (UCM)

• Use case models describe on an abstract level the collaboration of actors (users) with a system (computer)

• Use-case models define:

- Actors: what is outside the system

- Use case: what the system should achieve

• Tasks of the use case model are:

- Limiting the system (a simple rectangle symbolizes the system borders)

- Describing the functionality (from the user’s point of view)

The use case model can be understood to be the contract between customer and developer.3.

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Elements of the UCM

• Actor: - Are all participants that must exchange

information with the system

- Doesn‘t have to be a person

- Can be another system that communicates with the compiled system

• Use Case:- Can contain more than 1 user scenario

- Describes how a business transactionshould run through the interaction of an actor with the system and

- Which steps the user must undertake in order to manage a specific operation.

Actor Use cases

System border

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Relationships between use cases and actors (1)

• An inheritance hierarchy between actors is possible: when different actors can play similar roles, that means that they inherited these roles from the abstract actors

• The following relationship exists between the use cases:

- The “extended“ relationshipshows that a use case extends another use case

- The “uses” relationship lets us see that inside a use case, another use case appears - but which also could have appeared alone.

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Employee


Relationships between use cases and actors (2)

• Use cases can be linked to each other, the 3 usual relations are:

• <<uses>> or also <<include>>, that reveales that a use case takes place in anotheruse case.

• <<extends>>, that reveales that in a given situation, the use case is extended byanother use case.

• The ‚extends‘-relation is represented similar to the ‚uses‘-relation by a dashed linewith arrow:

System

Open CAD-File(local)

Printengineering drawing

«uses»«extends»

Open CAD-File(through PLM)

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Example of a Use Case Diagram

actorsUse cases

System borders

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Employee


Outline

Lecture Content







1. Preface

3.1.1. Introduction




3.2.1. Intro

3.2.5. Summary

2. Basics



Use case diagrams



Static Models




Inte

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Dynamic Models



Sequence-diagrams



Use cases




Act

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Class and instance diagrams

• Class and instance diagrams are static diagrams

• Representation method for the graphic notation and semantics for the modeling of objects, classes, and their relations

• Instance diagrams are used for describing not only the test cases, but also the scenarios or examples

• UML does not describe how classes shall be determined

• No visual differentiation between objects and classes - objects are distinguished from classes only through underscoring in their notation

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Representation of classes in class diagrams

• Class name: Naming of a class from the language area of application field. As the rule, a main word or an adjective (e.g., „vehicle“ or „civil vehicle“)

• Attribute: A data value (e.g., position, size, color,...). The objects of a class have the data value of this class

• Operation: A function (e.g., delay, delete, change size,..). Application to objects of a class Private attribute

Public operations

According to UML notation the class is represented in a rectangle and is comprised of:

Rectanglepositionsizecolor

move()delete()Change_size()Change_color()

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Object attribute

• An object attribute of a class is the description of a data element that is available in each object of the class. The name of the object attribute is given in the description of the class

• An object carries an individual and unchangeable attribute value for each object attribute

Notation:

Example:

Object : Classname

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Team meeting

titel: Stringbeginning: Dateduration: int

Classname1 D�� Attribute_1: data type

…Attribute_n: data type

Attribute_1 = Attributevalue_1…

Attribute_n = Attributevalue_n


ar12: Team meeting

title = „12. Department discussion “beginning = 5 -10-98 10:00

duration = 120 min

ar13: Team meeting

title = „13. Department discussion “beginning = 5 -17-98 10:00

duration = 120 min

ar14: Team meeting

title = „exhibition preparation “beginning = 5 -12-98 9:00

duration = 180 min

Team meeting

title: Stringbeginning: Dateduration: int

O C means „ O is an instance of C “

Object diagram with examples for object attributes

class Object

ObjectObject

Object attribute

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Class attribute

• A class attribute is the description of a data element that is only available once for all instances of a class.

• According to UML notation the class attributes are underlined.

Notation:

Example:

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Attribute1: datatypeAttribute1


ar12: Team meeting

title = „12. department discussion “beginning = 5 -10-98 10:00

duration = 120 min

ar13: Team meeting


duration = 120 min

ar14: Team meeting


duration = 180 min

Team meetingtheme: Stringbeginning: Dateduration: intquantity : 3

Object Diagram with an Example of Class Attributes

Class attribute

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Object operations

• An operation of an object is a description of a task which can be performed by every instance of the class. In the description of the class, the name of the operation is noted. The notation of a parameter list is possible but not necessary. Common operations are also called instance operations.

Notation: Example:

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Team meetingtitle: Stringbeginning: Dateduration: int

room_scheduling(): voidinvite(): boolean

cancel(): void

ClassnameAttribute_1: data type


Operation_1: return data type…

Operation_m: return data type


Object Diagram with an Example of Object Operations3.

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ar12: Team meeting


duration = 120 min

ar13: Team meeting


duration = 120 min

ar14: Team meeting


duration = 180 min


Class attribute

roomScheduling(): void

roomScheduling() roomScheduling()

roomScheduling()


Class Operations

• A class operation of a class is a description of a task which can be performed only with knowledge of all current instances of a class.

example:Notation:

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Meeting room

reservation(): booleanapproval(): boolean

Searchforfreeroom(): void

room_number: intcapacity: int

ClassnameAttribute_1: data type


Operation_1: return data type…

Operation_m: return data type


ar12: Team meeting


duration = 120 min

ar13: Team meeting


duration = 120 min

ar14: Team meeting


duration = 180 min


Object Diagram with an Example of Class Operations

Class attribute

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countMeetings(): int


Associations

• A (binary) association between two classes K1 and K2 is a description of a fact that the instances of both classes are having a functionally important relationship to each other

• For every object of the class K1, there is an individual, changeable and final amount of objects from the class K2, with which an association is made. The same is true for objects from K2

Notation:

example:

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Multiplicity of Associations

• The multiplicity is noted usually on both ends of the connection line. This tells how many objects can stand this relationship. Example: '1', '0..1', '0..*', '5..8', '5,8'

• There are differences between cardinality (# of elements) and multiplicity (area of allowed cardinality)

Notation:

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Class_1 Class_2Association

MultMultiplicity Mult :

n (exactly n object of the Class_2 )n..m (n till m objects of the Class_2 )

Also valid for n and m are 0 and * ( arbitrary . 0)


Multiplicity of Associations (Example)

• Class diagram:

The cardinality or multiplicity shows, howmany objects of one class are in relation withan object of another class.

It is shown by the indication of one number n (cardinality) or of a domain n..m or n..* (multiplicity), where * is an arbitrary numberfrom N0. Example: A professor can read

an arbitrary number oflectures, each lecture is readby one professor.A students attends 5 to 10lecture and in each lecturethere are 30 to * attendants.

LectureProfessorreads

attends

1 *

5…10

Student

30…*

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Documents

Computer Science for Engineers - KIT · software development process • UML is not a method, but rather a notation (description technique) • UML is independent from the developing