Requirements

Modeling OOTIF-151551

REKAYASA DAN MANAJEMEN KEBUTUHAN

Goals

Memahami konsep pemodelan OO pada rekayasa

kebutuhan.

Terampil dalam pembuatan diagram-diagram yang diperlukan

dalam pemodelan OO pada rekayasa kebutuhan.

Rekayasa dan Manajemen Kebutuhan | Requirements Modeling - OO

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Rekayasa dan Manajemen Kebutuhan | Requirements Modeling - OO

Object Oriented Approach

Mulai populer akhir 80an 90an (Booch, Rumbaugh-OMT, Jacobson-OOSE, Coad+Yourdon, Wirfs-Brock) :

Elisitasi kebutuhan customer

Identifikasi skenario / use-case (use-case diagram)

Identifikasi klas berdasarkan kebutuhan customer

Identifikasi atribut dan operasi setiap klas

Definisi struktur klas (class diagram)

Definisi model relasi antar klas (collaboration/sequence diagram)

Definisi perpindahan status sistem (statechart diagram)

1996 : UML (Unified Modeling Language) Grady Booch+James Rumbaugh+Ivar Jacobson

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Rekayasa dan Manajemen Kebutuhan | Requirements Modeling - OO

Diagram UML

Use-case diagram (statis) scenario-based models

Class diagram (statis) class models

Collaboration/sequence diagram (dinamis) behavioral models

Statechart diagram (dinamis) behavioral models

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Rekayasa dan Manajemen Kebutuhan | Requirements Modeling - OO

Keuntungan

Sangat natural, sesuai dengan cara berpikir manusia

improve analyst and problem domain expert interaction

Meningkatkan konsistensi hasil analisis abstraksi atribut-

operasi dalam sebuah objek

Konsep penurunan klas memberikan kemudahan dalam

generalisasi objek

Kemudahan dalam perubahan

Terjaganya konsistensi model antara analisis dan

perancangan

Konsep reusability

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Rekayasa dan Manajemen Kebutuhan | Requirements Modeling - OO

Object, Class Apa Itu ?

Objek (Object) :

A concept, abstraction, or thing with crisp boundaries and meaning for

the problem at hand [Rumbaugh]

Benda (tangible & intangible thing)

Contoh : Andi, Eko, Susi (sistem akademik)

Sebuah objek memiliki karakteristik : identity (identitas-pembeda), state

(sekumpulan atribut) & behavior (sekumpulan operasi, aksi, servis)

Notasi :Nama Objek

Atribut2

Operasi2

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Rekayasa dan Manajemen Kebutuhan | Requirements Modeling - OO

Object, Class Apa Itu ?

Klas (Class) : A description of one or more objects with a uniform set of attributes and

services, including a description of how to create new objects in the class

[Yourdon]

Gambaran umum (template, blue-print) yang menjelaskan sekumpulan

objek yang memiliki kesamaan karakteristik (atribut dan operasi)

Merupakan cetakan dari objek

Digunakan untuk menginstansiasi objek yang memiliki identitas yang

berbeda

Contoh : Klas Mahasiswa objek Andi, Eko, Susi

Abstract & concrete class

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Rekayasa dan Manajemen Kebutuhan | Requirements Modeling - OO

Object, Class Apa Itu ?

Mahasiswa

- NIM

- Nama

- Buat skripsi

- Ujian

Mahasiswa

- NIM : 001

- Nama : Andi

- Buat skripsi

- Ujian

Mahasiswa : Andi

Mahasiswa

- NIM : 002

- Nama : Eko

- Buat skripsi

- Ujian

Mahasiswa : Eko

Mahasiswa

- NIM : 003

- Nama : Susi

- Buat skripsi

- Ujian

Mahasiswa : Susi

Instansiasi : penciptaan objek

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Rekayasa dan Manajemen Kebutuhan | Requirements Modeling - OO

Where to look ?

Investigasi domain masalah

Langkah-langkah:

Observe first-hand observasi langsung ke lap.

Actively listen to problem domain experts what, who, why, when and

how

Check previous OOA results

Check other systems comparison

Read, read, read getting some more information

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Rekayasa dan Manajemen Kebutuhan | Requirements Modeling - OO

What to look for ? Nouns Structures

Relasi antar objek generalisasi, agregasi

Other systems

Sistem lain yang berinteraksi dg proposed system

Things or events remembered

Data, status, kejadian yang harus disimpan

Roles played

Identifikasi peran manusia dalam sistem berinteraksi

langsung, tidak berinteraksi tetapi informasinya disimpan

sistem

Sites

Informasi lokasi/posisi yang harus diingat oleh sistem

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Rekayasa dan Manajemen Kebutuhan | Requirements Modeling - OO

Identifikasi atribut

Some data (state information) for which each object in a class has its

own value [Yourdon]

Langkah-langkah:

Identifikasi atribut umum (adjectives, possessives)

Identifikasi atribut yang relevan dg domain masalah

Identifikasi atribut yang relevan dg peran atau tanggung jawab dalam

sistem

Restrukturisasi atribut sehingga atomic kemudahan

Reposisi atribut yang sesuai dengan hirarki klas nya pewarisan klas

Spesifikasi atribut presisi, nilai default, batasan, dll.

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Rekayasa dan Manajemen Kebutuhan | Requirements Modeling - OO

Identifikasi operasi/servis

A specific behavior that an object is responsible for exhibiting

[Yourdon]

Langkah-langkah:

Identifikasi tanggung jawab umum sebuah klas (verbs)

Identifikasi operasi yang spesifik untuk domain masalah

Identifikasi operasi yang relevan dg peran atau tanggung jawab dalam

sistem

Spesifikasi operasi argumen, batasan/aturan, logika/algoritma

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Rekayasa dan Manajemen Kebutuhan | Requirements Modeling - OO

Use-case diagram

Menjelaskan perilaku sistem dari tampak luar

Menyediakan fungsi-fungsi yg harus dipenuhi sistem sesuai dengan

aktornya

Elemen: actor (orang, sistem lain) dan use-case

Setiap use-case dilengkapi dengan skenario (deskripsi)

Langkah-langkah:

Identifikasi aktor

Identifikasi use-case per aktor

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Rekayasa dan Manajemen Kebutuhan | Requirements Modeling - OO

Use-case diagram

Select product

Get return coins

Customer

Enter object

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Rekayasa dan Manajemen Kebutuhan | Requirements Modeling - OO

Use-case scenario

Flow of events for the Select product use-case

Objective Allow customer to select a certain product to dispense

Actors Customer

Pre-condition Coin detected and valid

Main flow 1. The customer selects a button product.

2. The system displays an entry prompt of number of product to order.

Alternative flows 1. If the selected product is not available, the system will display a message Your selected product is not available.

2. If the selected product is available but there isnt enough number to order, the system will display a message The number isnt enough, max. x. X is the existing number of the product.

Post-condition The selected product dispensed as the number needed

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Rekayasa dan Manajemen Kebutuhan | Requirements Modeling - OO

Use-case association

Include

A use case uses another use case (functional decomposition) reuse

A function in the original problem statement is too complex to be solvable immediately describe the function as the aggregation of a set of

simpler functions (mandatory)

Extend

A use case extends another use case

The functionality in the original problem statement needs to be extended

The extended use-case plays an optional use-case

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Rekayasa dan Manajemen Kebutuhan | Requirements Modeling - OO

and

ViewMap

OpenIncident

AllocateResources

Base Use

CaseSupplier

Use Case

ReportEmergency

Help

A

B

Base Use

Case

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Rekayasa dan Manajemen Kebutuhan | Requirements Modeling - OO

Actor-generalization

Two/more sub-actors generalized into a super-actor

Have both behavior and attributes in common described under the

super-actor

Super-actor should interact with use cases when ALL of its sub-actors

interact in the same way

Sub-actors should interact with use cases when their individual

interactions differ from that of the super-actor

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Rekayasa dan Manajemen Kebutuhan | Requirements Modeling - OO

Actor-generalization

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Rekayasa dan Manajemen Kebutuhan | Requirements Modeling - OO

Class diagram

Menggambarkan struktur statis dari sistem

Terdiri dari node (klas) dan relasi

Jenis relasi

Generalization (is a inheritance)

Association

Aggregation (part-of)

Composition

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Rekayasa dan Manajemen Kebutuhan | Requirements Modeling - OO

Association

For real-world objects is there an association between classes?

Classes A and B are associated if:

An object of class A sends a message to an object of B

An object of class A creates an instance of class B

An object of class A has an attribute of type B or collections of objects of type B

An object of class A receives a message with an argument that is an instance of B (maybe) will it use that argument?

Does an object of class A need to know about some object of class B?

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Rekayasa dan Manajemen Kebutuhan | Requirements Modeling - OO

Aggregation composition

Aggregation represents a part-whole or part-of relationship

Aggregation can occur when a class is a collection or

container of other classes, but where the contained classes

do not have a strong life cycle dependency on the container

essentially, if the container is destroyed, its contents are not

Composition is more specific than aggregation

Composition usually has a strong life cycle dependency

between instances of the container class and instances of the contained class(es) if the container is destroyed, normally

every instance that it contains is destroyed as well

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Rekayasa dan Manajemen Kebutuhan | Requirements Modeling - OO

Class relationships examples

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Rekayasa dan Manajemen Kebutuhan | Requirements Modeling - OO

Class stereotypes

Boundary classes

model the interaction and manage communication between the

computer system and its actors, but dont directly represent the specific

interface object in the implementation

used to identify the main logical interfaces with users and other systems

(including e.g. other software packages, printers)

main task is to translate information across system boundaries

partition the system so that interface is kept separate from business logic

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Rekayasa dan Manajemen Kebutuhan | Requirements Modeling - OO

Class stereotypes

Entity classes

used to model data and behavior of some real life system

concept or entity e.g. member, bank account, order, employee

these will sometimes require more persistent storage of information

e.g. a students details are ultimately stored as a student record

Control classes

represent coordination, sequencing, transactions and control of

other objects

glue between boundary elements and entity elements, describing

the logic required to manage the various elements and their

interactions

roughly one per use case

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Rekayasa dan Manajemen Kebutuhan | Requirements Modeling - OO

Class stereotypes

Model interaction between the system and its

environment

Actor 1

Actor 2

boundary entity control

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Rekayasa dan Manajemen Kebutuhan | Requirements Modeling - OO

Sequence diagram

An interaction diagram that emphasizes the

time ordering of messages

Shows a set of objects and the messages sent

and received by those objects

Elements

Object represented in a box

Dashed line called the object lifeline, and it represents the existence of

an object over a period of time

Message rendered as horizontal arrows being passed from object to

object as time advances down the object lifelines

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Rekayasa dan Manajemen Kebutuhan | Requirements Modeling - OO

Sequence diagram example

: Customer : SelectionScreen : SelectionController : Products :

DispenserProduct

selectProduct( )getValidSelection(String)

isProductAvailable(String)

dispenseProduct(String, int)

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Rekayasa dan Manajemen Kebutuhan | Requirements Modeling - OO

Statechart diagram

A statechart diagram shows the behavior of classes in response to

external stimuli

This diagram models the dynamic flow of control from state to state

within a system

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Rekayasa dan Manajemen Kebutuhan | Requirements Modeling - OO

Statechart diagram example

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Waiting for a coin

Waiting for selection

Dispensing product

Returning payment

initial

accept new coin

payment returned

accept new coincoin detected

accept customer

requestproduct dispensed

accept new coin

sufficient payment

dispense product

product

available=FALSE

return payment

coin return request

return payment