ANALISIS DAN PERANCANGAN
SISTEM (APS)
Pemodelan Kebutuhan:
Tujuan perkuliahan
Memahami konsep pendekatan berorientasi objek
dalam pemodelan kebutuhan
Agenda
Konsep pemodelan berorientasi objek
Elemen-elemen pemodelan berorientasi objek
Dokumentasi dan alat bantu
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
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
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) &
behaviour (sekumpulan operasi, aksi, servis)
Notasi :
Nama ObjekAtribut2 Operasi2
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
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 objekWhere 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
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
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
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
Diagram UML
Use-case diagram (statis)
Class diagram (statis)
Collaboration/sequence diagram (dinamis)
Statechart diagram (dinamis)
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
Use-case diagram
Select product
Get return coins Customer
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.
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
<<include>> and <<extend>>
ViewMap OpenIncident AllocateResources <<include>> <<include>> Base Use Case Supplier Use Case ReportEmergency Help <<extend>> A B Base Use CaseActor-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
Class diagram
Menggambarkan struktur statis dari sistem
Terdiri dari node (klas) dan relasi
Jenis relasi
– Generalization (‘is a’ – inheritance) – Association
– Aggregation (‘part-of’) – Composition
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?
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
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
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
Class stereotypes
Model interaction between the system and its environment
Actor 1 <<boundary>> <<control>> <<boundary>> <<entity>> <<entity>> Actor 2
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
Sequence diagram – example
: Customer : SelectionScreen : SelectionController : Products :
DispenserProduct
selectProduct( )
getValidSelection(String)
isProductAvailable(String)
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
Statechart diagram – example
Waiting for a coin Waiting for selection Dispensing product Returning payment initial accept new coinpayment returned accept new coin coin detected
accept customer request product dispensed
accept new coin
sufficient payment dispense product
product available=FALSE
return payment coin return request
Alat bantu
Structured Analysis :
– Aplikasi pengolah model : Visio, dll. – Aplikasi pengolah kata : MS Word, dll.
– CASE Tool : StP (Software through Picture), PSL/PSA (Problem Statement Language/Problem Statement
Anaylzer), ILeaf, SPMS, dll.
OO Analysis :
– Aplikasi pengolah model : Visio, dll. – Aplikasi pengolah kata : MS Word, dll.
– CASE Tool : Rational RequisitePro, Rational Soda for Word, Rational Rose, ArgoUML, dll.
Dokumentasi
IEEE Standard+ (IRS/SRS):
1. Introduction
1.1. Purpose of the requirements document 1.2. Scope of the product
1.3. Definition, acronyms and abbreviations 1.4. References 2. General Description 2.1. Product perspective 2.2. Product functions 2.3. User characteristics 2.4. General constraints 3. Specific Requirements
All functional and non-functional requirements, system models (eg. DFD/CFD, ERD, STD, Use-Case, Class, Sequence, Statechart diagrams), performance, database requirements, design constraints, security.
3. Qualification/Validation Requirements
