ANALISIS DAN PERANCANGAN SISTEM (APS)

  Pemodelan Kebutuhan: Pendekatan Berorientasi Objek

  Tujuan perkuliahan

Memahami konsep pendekatan berorientasi objek

dalam pemodelan kebutuhan

  2/34 Agenda Konsep pemodelan berorientasi objek Elemen-elemen pemodelan berorientasi objek Dokumentasi dan alat bantu

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  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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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 _5/34

  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)

  identity

• – Sebuah objek memiliki karakteristik :

  state

  (identitas-pembeda), (sekumpulan atribut) &

  behaviour

  (sekumpulan operasi, aksi, servis)

  Nama Objek

Notasi :

  Atribut2 Operasi2 _6/34

• – 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

  7/34 Object, Class

• – Apa Itu ?
• Ujian
• Ujian

  Bahan Kuliah APS - Pemodelan Kebutuhan: OO | Tri A. Kurniawan, S.T, M.T, Ph.D 8/34 Object, Class

  Mahasiswa _- NIM _{- Nama - Buat skripsi}

  Mahasiswa _- NIM : 001 _{- Nama : Andi - Buat skripsi}

  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

  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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• – Relasi antar objek  generalisasi, agregasi
• – Sistem lain yang berinteraksi dg proposed system
• – Data, status, kejadian yang harus disimpan
• – Identifikasi peran manusia dalam sistem  berinteraksi langsung, tidak berinteraksi tetapi informasinya disimpan sistem
• – Informasi lokasi/posisi yang harus diingat oleh sistem

  10/34 What to look for ? Nouns

  Structures

  Other systems

  Things or events remembered

  Roles played

  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

• – Spesifikasi atribut presisi, nilai default, batasan, dll. _11/34
• – Identifikasi tanggung jawab umum sebuah klas

• – 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

  12/34 Identifikasi operasi/servis

  A specific behavior that an object is responsible for exhibiting [Yourdon]

Langkah-langkah:

  (verbs)

  Diagram UML Use-case diagram

  (statis) Class diagram

  (statis) Collaboration/sequence diagram

  (dinamis) Statechart diagram

  (dinamis) 13/34

  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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  Bahan Kuliah APS - Pemodelan Kebutuhan: OO | Tri A. Kurniawan, S.T, M.T, Ph.D 15/34 Use-case diagram

  Select product Get return coins Customer

  Enter object

  Bahan Kuliah APS - Pemodelan Kebutuhan: OO | Tri A. Kurniawan, S.T, M.T, Ph.D 16/34

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

• – 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)
>– 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

  17/34 Use-case association

  Include

Extend

  Bahan Kuliah APS - Pemodelan Kebutuhan: OO | Tri A. Kurniawan, S.T, M.T, Ph.D 18/34 <<include>> and <<extend>>

  ViewMap ^OpenIncident AllocateResources ^{<<include>> <<include>>} Base Use Case

  Supplier Use Case ReportEmergency ^{Help <<extend>>}

  A B

  Base Use Case

  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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  Bahan Kuliah APS - Pemodelan Kebutuhan: OO | Tri A. Kurniawan, S.T, M.T, Ph.D 20/34 Actor-generalization

  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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  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? _22/34

  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 _23/34

  Bahan Kuliah APS - Pemodelan Kebutuhan: OO | Tri A. Kurniawan, S.T, M.T, Ph.D 24/34 Class relationships – examples

  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
_25/34

  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
_26/34

  Bahan Kuliah APS - Pemodelan Kebutuhan: OO | Tri A. Kurniawan, S.T, M.T, Ph.D 27/34 Class stereotypes

  Model interaction between the system and its environment Actor 1

  <<boundary>> <<control>>

  <<boundary>> <<entity>> <<entity>> Actor 2 boundary entity control

  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
_28/34

  Bahan Kuliah APS - Pemodelan Kebutuhan: OO | Tri A. Kurniawan, S.T, M.T, Ph.D 29/34 Sequence diagram – example

  : Customer : SelectionScreen : SelectionController ^{: Products :} _{DispenserProduct selectProduct( )} getValidSelection(String) _{isProductAvailable(String)} dispenseProduct(String, int)

  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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  Bahan Kuliah APS - Pemodelan Kebutuhan: OO | Tri A. Kurniawan, S.T, M.T, Ph.D 31/34 Statechart diagram – example

  Waiting for a _coin Waiting for _selection

  Dispensing _product ^{Returning payment initial accept new coin payment 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 return payment} 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. _32/34

  Dokumentasi

  IEEE Standard+ (IRS/SRS):

  1.1. Purpose of the requirements document

  1.2. Scope of the product

  1.3. Definition, acronyms and abbreviations

  1.4. References

  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

  4. Appendices/Bibliography _33/34

  Summary Pemodelan berorientasi objek meliputi use-case, class

  , sequence dan state dari sistem yang sedang dikembangkan Alat bantu yang digunakan dalam pemodelan terstruktur dan berorientasi objek terdapat perbedaan Dokumentasi yang dihasilkan dari RE terdiri IRS dan SRS

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