OO Development 3 - Models And UML

MODELING AND UMLOVERVIEW

3

2

ANALYSIS5

INTRODUCTION1METHODOLOGIES2MODELS AND UML3OBJECT CONCEPTS4

SOFTWARE DESIGN6

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Goal of Presentation3

This presentation will Define model and diagrams and explain

importance of them to system development.

Introduce UML

Definitions4

A model is a simplified representation of something in the real world, usually for the purpose of understanding that reality, and having all the features of that reality necessary for the current task or problem. Like a map, a model represents something else.

Thus modeling is a form of abstraction, that is, the process of focusing only on features essential to the problem at hand.

Source: David William Brown, An Intro to Object-Oriented Analysis (Wiley, 2002), p. 30

What Are Models For?5

Models are used for: To capture and precisely state requirements

and domain knowledge so that all stakeholders may understand and agree on them.

To think about the design of a system. To capture design decisions in a mutable form

separate from the requirements. To generate usable work products. To organize, retrieve and edit info about large

systems. To explore multiple solutions economically. To master complex systems.

Source: Rumbaugh, Jacobson, Booch, Unified Modeling Language Reference Manual (Addison-Wesley, 1999), p. 13-4

Levels of Models6

Models take on different forms and appear at different levels of abstraction. A useful model has the right level of detail and

represents only what is important for the task in hand.

The amount of detail in the model is adapted to one of the following purposes: Guides to the thought process. Abstract specifications of the essential structure of a

system. Full specification of a final system. Exemplars of typical or possible systems. Complete or partial descriptions of systems.


Many Matching Models7

Each model emphasizes some aspect of the real-world thing.

Thus, many models are required to reveal all the important details of that thing.

Yet, these matching models must eventually fit together. What is represented in one model must be

consistent with what is represented in another model.

Source: Satzinger and Orvik, The Object-Oriented Approach (Course Technology, 2001), p. 51

8


Diagrams9

Diagrams are abstract shapes that are used to represent things or actions from the real world

Diagrams follow rules or standards The standards make sure that different

people will interpret the diagram in the same way

Source: Bennett, McRobb, and Farmer, Object-Oriented Systems Analysis and Design (McGraw Hill, 2002), p. 98-9.

40°

An Example of a Diagram

10

An activity diagram of the tasks involved in producing a book.

Write Chapter

Review Chapter

Author PrinterTypesetterReviewer

Typeset Book

Correct Proofs

Reset Book

Print Book

[book complete]

[book notcomplete]

Revise Chapter

Source: Bennett, McRobb, and Farmer, Object-Oriented Systems Analysis and Design presentation.

Hiding Detail11

Write Chapter

Review Chapter

Author PrinterTypesetterReviewer

Typeset Book

Correct Proofs

Reset Book

Print Book

[book complete]

[book notcomplete]

Revise Chapter

Plan Chapter

Produce First Draft

Revise Draft

[satisfied]

[not satisfied]

Add Exercises

Add Referencesto Bibliography

Write Chapter


Diagrams versus Models 12

A diagram illustrates some aspect of a system.

A model provides a complete view of a system at a particular stage and from a particular perspective.

A model may consist of a single diagram, but most consist of many related diagrams and supporting data and documentation.


Models in Systems Development

13

To understand the user’s world we need: People sensitivity (interviewing and listening

skills) for gathering relevant and accurate information.

Modeling diagrams to document and communicate what we’ve learned from the users. We are using UML as our modeling notation.

Modeling techniques to ensure these notations produce an accurate picture of the user’s business. These are partly defined by:

the modeling notation itself, as well as the software process/methodology.

Source: David William Brown, An Intro to Object-oriented (Wiley, 2002), p. 38

Developing Models14

The models that we produce during the development of a system change as the project progresses.

They change by degree of: Abstraction

Model will become less abstract and more concrete. Formality

Degree of formality in which methods, attributes, and constraints are defined will increase as project progress.

Level of detail More potential detail in every model as project

progresses.


15

Iteration 1Obvious use cases.Simple use case descriptions.

Iteration 2Additional use cases.Simple use case descriptions.Prototypes.

Iteration 3Structured use cases.Structured use case descriptions.Prototypes.

Assign staff to work on

a campaign

Campaign Manager

Add a new advert to

a campaign

Check campaign budget

Find campaign

Accountant

summary Print campaign

invoice

«include»

«extend» «extend»

Print campaign

«include»

«include»

Campaign Management


a campaign

Campaign Manager

Add a new advert to

a campaign


Find campaign

Accountant


invoice

«include»


Print campaign

«include»

«include»

Campaign Management

Calculate staff bonuses

Accountant

Add a new staff member

Add a new staff grade

Change the rate for a

staff grade

Change the grade for a

staff member

Staff Management


Accountant




staff grade


staff member

Staff Management


Accountant




staff grade


staff member

Staff Management


Accountant




staff grade


staff member

Staff Management


Accountant




staff grade


staff member

Staff Management


a campaign

Campaign Manager

Add a new advert to

a campaign


Find campaign

Accountant


invoice

«include»


Print campaign

«include»

«include»

Campaign Management

Spring Jewellery Campaign 1997Spring Jewellery Campaign 2001Spring Jewellery Campaign 2002Summer Collection 1998

OK Quit

Campaign:

Campaign Selection

Holborn MotorsLynch PropertiesYellow Partridge Zeta Systems

Client:

Yellow Partridge


OK Quit

Campaign:

Campaign Selection


Client:

Yellow Partridge

Spring Jewellery Campaign 2002

OK Quit

Campaign:

Campaign Selection


Client:


OK Quit

Campaign:

Campaign Selection


Client:

Yellow Partridge


OK Quit

Campaign:

Campaign Selection


Client:

Yellow Partridge

Spring Jewellery Campaign 2002

OK Quit

Campaign:

Campaign Selection


Client:

Source: Bennett, McRobb, and Farmer, Object-Oriented Systems Analysis and Design (McGraw Hill, 2002), p. 104.

Development of Use Case Model through successive iterations


Earlier Models and Diagrams

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A variety of modeling notations have developed over the years. These include: Process models (data flow diagrams) Data models (ERDs)

Process Models: Data Flow Diagrams

17

Focus not just on operations but on who does what with whom. That is, the focus is on data and how it processes through an organization.

Used Data Flow Diagrams (DFDs) as a way to model the activities, functions, and processes that make up a users’ business.

Courses

StudentRecords

Enrollments

Registration

Enrollment

Student

Student Details

Acknowledgementof Registration

Enrollment Request

EnrollmentConfirmation

Validated StudentDetails

Confirmation ofEnrollment

VacanciesConfirmed

Enrollments

Data Models: ERDs18

Focus on data modeling rather than on process modeling.

Entity Relationship Diagrams (ERDs) used as analysis tool as well as a database design tool.

OO Diagramming19

There are all sorts of different OO diagrams: e.g., Booch OOD, Rumbaugh OMT, Yourdon & Coad,

etc. UML (Unified Modeling Language) has

become the standard notation for OO diagramming and modeling. The modeling notation defined by UML does not

define a modeling technique These are defined by the software process/methodology.

UML is not a methodology or process; rather it is a universal modeling notation.

UML Defined20

The Unified Modeling Language (UML) is a general purpose visual modeling language that is used to specify, visualize, construct, and document the artifacts of a software system.

Source: Rumbaugh, Jacobson, Booch, Unified Modeling Language Reference Manual (Addison-Wesley, 1999), p. 3

UML Defined21

It captures decisions and understanding about systems that must be constructed.

It is used to understand, design, browse, configure, maintain, and control information about systems.

It is intended to be used with all development methods, lifecycle stages, application domains, and media.


Not A Programming Language!

22

The UML is not a programming language !

The UML is a general-purpose modeling notation for discrete systems such as software.

Goals of UML23

There were a number of goals behind the development of UML: UML is a general-purpose modeling language that all

modelers can use. It is meant to include the concepts of the leading

methods so that it can be used as their modeling language.

It was intended to be as familiar as possible. It is meant to support good practices for design such as

encapsulation, separation of concerns, and capture of the intent of a model construct.

It is intended to address current software development issues, such as large scale, distribution, concurrency, patterns and team development.

It was to be as simple as possible while still being capable of modeling the full range of practical systems that need to be built.


What Does Unified Mean?24

The word unified has the following relevant meanings for UML: Across historical methods and notations. Across the development lifecycle Across application domains Across implementation languages and

platforms Across development processes Across internal concepts


UML Building Blocks25

UML is composed of three building blocks: Things

These are the modeling elements Relationships

These tie things together Diagrams

These are views into UML models

Source: Booch, The Unified Modeling Language User Guide (Addison-Wesley, 1998), p. 2.

UML Things26

UML thing may be partitioned into: Structural things

Represent the nouns of a UML model such as class, component, use case, etc

Behavioral things Represent the verbs of a UML model such as

interactions, states, etc. Grouping things

Represent things that group elements together such as the package.

Annotational things The note

Source: Arlow and Neustadt, UML and the Unified Process (Addison-Wesley, 2002), p. 9.

UML Relationships27

Used to show how two or more things relate to each other.

generalization association

dependency realization


Diagrams in UML28

UML diagrams consist of: icons two-dimensional symbols paths Strings

UML diagrams are views into the model. They are not the model itself

Plan Chapter

Produce First Draft

Revise Draft

[satisfied]

[not satisfied]

Add Exercises

Add Referencesto Bibliography

Write Chapter


UML Diagrams29

Static Model Dynamic Model

class diagram

component diagram

deployment diagram

object diagram

use case diagram

sequence diagram

collaboration diagram

statechart diagram

activity diagram


UML Parts30

A system is modeled as a collection of discrete objects that interact to perform work that ultimately benefits an outside user.

UML has: static and, dynamic parts.


Static and Dynamic Information

31

In particular UML captures information about the static structure and the dynamic behavior of a system. The static structure defines the kinds of objects important to a system

and to its implementation, as well as the relationships among the objects.

The dynamic behavior defines the history of objects over time and the communications among objects to accomplish goals.


Organization32

The UML also contains organization constructs for arranging models into packages that permit software teams to: partition large systems into workable pieces. understand and control dependencies among

the packages, and manage the versioning of model units in a

complex development environment. The UML contains constructs for

representing implementation decisions and for organizing run-time elements into components.


UML Concepts33

system The overall thing that is being modeled.

sub-system Part of the system.

model An abstraction of system or subsystem from a

particular perspective or view. Different models present different views of the

system. diagram

A graphic representation of a set of elements in the model.

Source: Bennett, McRobb, and Farmer, Object-Oriented Systems Analysis and Design (McGraw Hill, 2002), p. 102.

Static Structure34

Any precise model must first define the universe of discourse. That is, the key concepts from the application, their

internal properties, and their relationships to each other.

This set of constructs is the static view of the system.

The static view is notated by class diagrams (also called class static structure diagrams). That is, the application concepts are modeled as classes,

each of which describes a set of discrete objects that hold information and communicate to implement behavior.


Class static structure diagrams

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-serviceCharge

+deposit()+withdrawal()

CheckingAccount

-interestRate

+makePayment()+addInterest()

Loan

BankAccount

-customerName-accountNum-balance

+getCustomerName()+getAccountNum()+getBalance()+setBalance()

Customer

Dynamic Behavior36

There are two ways to model behavior: One is the communication patterns of a set of

connected objects as they interact to implement behavior. This is modeled using use case diagrams,

sequence diagrams, collaboration diagrams, and activity diagrams.

The other is the evolution of an object’s state over time as it interacts with the rest of the world. State change refers to possible changes in object’s

attributes and associations with other objects. This is modeled as a statechart.


Use Cases37

When we analyze a system we try to identify the main functionality that the system will have and the main ways it will be used.

Each of these ways the system is going to be used is called a use case. A use case is a sequence of actions a system

performs that yields an observable result of value to a particular actor. An actor is either a person (user) interacting with

the system or, in some cases, another system interacting with the system.


Using Use Cases38

A use case captures the main functionality of the system from a user or actor’s perspective.

It also serves as a vehicle to divide the system into parts that can be implemented somewhat separately. For any given system, we will usually develop and

implement the most important use cases first. Establishing which use cases are important often

follows from looking at the main events in the problem domain.


Use Case Diagram39

We can model use cases in a use case diagram. Stick figures represent actors. Ovals represent the use case. The arrows show interactions.Video Store System

Video Store Clerk

Rent Videos

Add New Videos

Activity Diagrams40

Used to model business activities/tasks in the very early stages of a project.

Also used to describe a system function described by a use case.

They are analogous to standard flowcharts.

Activity Diagrams41

[campaign to add]

[new campaign]

Add a New Client

Assign StaffContact

Add New Campaign

activities

transitions

decisions

:Campaign

object flow

object

Activity Diagrams42

Swimlanes vertical columns labelled with the

person, organisationor departmentresponsible for theactivities in thatcolumn

Record Completionof a campaign

Issue invoice

CampaignManager

ClientAccountant

Pay invoice

Record clientpayment

Sequence Diagrams43

The class diagram is limited in that it does not represent time-dependent behaviors.

Sequence diagrams present object interactions arranged in time sequence. It shows the actors or objects participating in

an interaction and the events they generate arranged in a time sequence.

Often, a sequence diagram shows the events that result from a particular instance of a use case but a sequence diagram can also exist in a more generic form.


Sequence Diagrams44

Rectangles represent objects.Stick figures represent actors.Vertical lines represent the lifeline of the object or actor.Horizontal arrows indicate messages.

Patron Librarian

SubmitResources()

System

RecordID()

status()

SubmitLibraryCard()

RecordCallNumber()

CheckStatus()

CalcDueDate()

RecordLoan()

dueDate()

Collaboration Diagram45

A collaboration diagram shows interactions organized around the objects and their messages to each other. Collaboration diagrams and sequence

diagrams are used interchangeably. Unlike a sequence diagram, a collaboration

diagram shows relationships among object roles and it does not express time as a separate dimension.

ClassAInstance ClassBInstance

2: Message2()3: Message3()Message1()

Statechart Diagram46

The statechart diagram shows the states an object might be in and the actions or conditions that cause an object to make a transition from one state to another.

By documenting events and transitions, a statechart diagram shows the sequence of states an object goes through during its life.

Statecharts are extensions of the class diagram and you could create one statechart for each class. In practice, you will only create a statechart for

those classes that exhibit especially interesting or complex time-dependent behavior.


Statechart Diagram47

Boxes represent states.Arrows represent transitions between states.Solid dots represent start and end states.

Retrieving Books Packaging

Shipped ShippingsetFulfilledFlag

Model Organization48

Computers can deal with large flat models, but humans cannot.

In a large system, modeling information must be divided into coherent pieces so that teams can work on different parts concurrently.

Packages are general-purpose hierarchical organizational units of UML models. Packages can be used for storage, access

control, configuration management, and constructing libraries that contain reusable model fragments.


Packages49

If the class diagram becomes large, it will become quite difficult to use for an overview of the system. In such cases we create a high-level view of

the system, using some kind of partitioning or cluster scheme.

UML calls these clusters packages and provides modeling notation called a package diagram.

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