Requirements Modeling OO TIF REKAYASA DAN MANAJEMEN KEBUTUHAN

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1 Requirements Modeling OO TIF REKAYASA DAN MANAJEMEN KEBUTUHAN

2 2 Goals Memahami konsep pemodelan OO pada rekayasa kebutuhan. Terampil dalam pembuatan diagram-diagram yang diperlukan dalam pemodelan OO pada rekayasa kebutuhan.

3 3 Object Oriented Approach Mulai populer akhir 80an 90an (Booch, RumbaughOMT, 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

4 4 Diagram UML Use-case diagram (statis) Class diagram (statis) scenario-based models class models Collaboration/sequence diagram (dinamis) Statechart diagram (dinamis) behavioral models behavioral models

5 5 Keuntungan Sangat natural, sesuai dengan cara berpikir manusia improve analyst and problem domain expert interaction Meningkatkan konsistensi hasil analisis operasi dalam sebuah objek abstraksi atribut- Konsep penurunan klas memberikan kemudahan dalam generalisasi objek Kemudahan dalam perubahan Terjaganya konsistensi model antara analisis dan perancangan Konsep reusability

6 6 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

7 7 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

8 8 Object, Class Apa Itu? Mahasiswa - NIM Instansiasi : penciptaan objek - Nama - Buat skripsi - Ujian Mahasiswa : Andi Mahasiswa : Eko Mahasiswa : Susi Mahasiswa Mahasiswa Mahasiswa - NIM : NIM : NIM : Nama : Andi - Nama : Eko - Nama : Susi - Buat skripsi - Buat skripsi - Buat skripsi - Ujian - Ujian - Ujian

9 9 Where to look? Investigasi domain masalah Langkah-langkah: Observe first-hand observasi langsung ke lap. Actively listen to problem domain experts how what, who, why, when and Check previous OOA results Check other systems Read, read, read comparison getting some more information

10 10 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

11 11 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 Spesifikasi atribut presisi, nilai default, batasan, dll. pewarisan klas

12 12 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

13 13 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

14 14 Use-case diagram Ent er object Customer Select product Get return coins

15 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 The customer selects a button product. 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. 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. 2. Post-condition The selected product dispensed as the number needed 15/54

16 16 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

17 17 <<include>> and <<extend>> <<include>> OpenIncident ViewMap Base Use Case <<include>> Supplier Use Case AllocateResources Base Use Case B Help A ReportEmergency <<extend>>

18 18 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

19 19 Actor-generalization

20 20 Class diagram Menggambarkan struktur statis dari sistem Terdiri dari node (klas) dan relasi Jenis relasi Generalization ( is a inheritance) Association Aggregation ( part-of ) Composition

21 21 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 22 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 23 Class relationships examples

24 24 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 25 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 26 Class stereotypes <<control>> <<boundary>> Actor 1 <<boundary>> Actor 2 <<entity>> <<entity>> Model interaction between the system and its environment boundary entity control

27 27 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 28 Sequence diagram example : Customer : SelectionScreen : SelectionController : Products selectproduct( ) getvalidselection(string) isproductavailable(string) dispenseproduct(string, int) : DispenserProduct

29 29 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

30 30 Statechart diagram example initial accept new coin Waiting for a coin payment returned coin detected product dispensed accept new coin accept customer request coin return request return payment Returning payment Waiting for selection sufficient payment dispense product Dispensing product accept new coin product available=false return payment