requirements modeling –oo · object, class –apa itu ? ... display a message “your selected...
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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 isn’t enough number to order, the system will display a message “The
number isn’t 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
<<include>> and <<extend>>
ViewMap
OpenIncident
AllocateResources
<<include>>
<<include>>
Base Use
CaseSupplier
Use Case
ReportEmergency
Help
<<extend>>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 don’t 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 student’s 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<<boundary>>
<<control>>
<<boundary>>
<<entity>> <<entity>>
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