Desain slide ini dadaptasi dari University of San Fransisco
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
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