9. expanded use case -...

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9. Expanded Use Case

SIF15001

Analisis dan Perancangan Sistem Informasi

Agi Putra Kharisma, S.T., M.T.

Genap 2014/2015

Unified Process

Di sini

Apa yang dikerjakan?

Detailing or expanding a use case into a sequence of steps corresponds to refining the requirements analysis, especially the functional

requirements.

Technology and interfaces should be ignored at this point.

Langkah Membuat Expanded Use Case

1. Main Flow/Scenario

2. Alternate Flow/Scenario

Disebut juga happy path, karena tidak

mengandung error, failure, atau

exception.

Variant

Exception

1. Main Flow/Default Sequence

the description of the use case process when everything goes right, that is, when no

alternate flow occurs.

Contoh Draft Expanded Use Case Versi 1 (1)

Contoh Draft Expanded Use Case Versi 1 (2)

2. Alternate Flow

A use case specifies a process that can be performed in real life in a number of different

ways.

Penting...

Exceptions, however, instead of producing conditional tests in the main flow, must be

ignored by it, and handled separately.

Contoh Yang Tidak Baik

x

x

x

Dapat membingungkan....

Variants

• More than one possible ending. • Not a condition that prevents the use case

from concluding, because the use case still produces something.

Contoh Variant: 1

Pada use case Buy Books (gabungan dari use case

Order Books dan Pay Order), pembeli memiliki dua

pilihan, membayar sekarang atau menunda pembayaran

(menyimpan barang pada shopping chart).

Solusi 1 (1/3)

Solusi 1 (2/3)

Solusi 1 (3/3)

Contoh solusi lainnya...

Solusi 2 (1/2)

Solusi 2 (2/2)

Menentukan Jumlah Use Case Berdasarkan Skenario

Contoh kasus:

• A customer orders books and saves the shopping cart

to continue shopping later.

• A customer orders books and pays for them.

Apakah kasus di atas dijadikan 2 buah use case terpisah?

Ataukah dijadikan sebuah use case dengan 2 buah alternatif?

Masing – masing keputusan memiliki plus dan minusnya.

Exception Handling

Exception is an event that if not handled prevents a

process from proceeding.

Interesting exceptions in a use case flow are those in which

the user tries to send information that the system cannot

accept.

Each exception must be handled by an alternate flow that

corresponds to a branch of the main flow.

Contoh Use Case Dengan Exception

Exception Handler

An exception handler has at least four parts:

1. An identification code that consists of the number of the

step(s) that originates the exception followed by a letter

that identifies the exception.

2. The exception, which consists of a sentence that states

which business rule was broken

3. Corrective actions that consist of an alternate flow, that

is, a sequence of actions that should be performed to

correct the exception.

4. Finalization, which is the last line of the alternate flow and

indicates if and how the use case returns to the main flow

after performing the corrective actions.

Mandatory Steps

Depending on the direction the information goes, mandatory

steps may be identified as:

• System events [IN]: Steps that indicate that some

information is transmitted from the actors to the system.

• System returns [OUT]: Steps that indicate that some

information is transmitted from the system to the actors.

Contoh Use Case Dengan Mandatory Steps

Complimentary Steps

Complimentary steps does not represent an information flow between actors and the

system

Contoh:

• “the customer opens the bookstore homepage,”

• “the customer decides to buy books,”

• “the system asks the customer for identification,”

• ..etc

Unsuitable Steps

Use case yang mendeskripsikan sistem proses internal.

Ini harus dihindari!

Contoh included use cases and fragments (1/2)

Contoh included use cases and fragments (2/2)

Preconditions & Success Postconditions

• Preconditions are facts considered true before a use case

even starts.

• Success post conditions establish the results of a use

case, that is, what will be true after the use case is

executed.

Referensi

Raul Sidnei Wazlawick - Object-Oriented Analysis and Design

for Information Systems