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Lecture

ITM 305 Lecture Notes - Canter And Gallop


Department
Information Technology Management
Course Code
ITM 305
Professor
Youcef Derbal

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USE CASE MODELING
REVIEW
Requirement Specification
Data Dictionary and Context Diagram, List of Natural Statements
(Requirement Set), Problem Statement
They use natural language (rich, nuanced, not constrained), English
Challenging to communicate requirements precisely and
unambiguously ......
Use Case Modeling
Use Case Diagram, Activity Diagram, Use Case Description
How the system shall behave to satisfy the user requirements
They use UML (Unified Modelling Language)
Facilitate communication between Analysts, Designers, Clients,
Managers, etc
Amenable to standard methods of analysis
Useable throughout the software life cycle
Context Diagram
Shows the boundaries of the system and the category of users expected to
interact with the system (Actors)
Use Case Diagram
Specifies of the “pieces” of system functional behaviour that would satisfy
the itemized of user requirement
Each major/coherent functional behaviour “piece” is called a Use Case
It is the process of moving “ what the user wants from the system” to “how
the system shall behave to satisfy it”
There is no reference to the internal structure of the system
It doesn’t care about how the system should be made
Use Case
Example: System Sequence of Actions
1) The customer submit a completed payment form
2) The System validates the customer’s payment information
3) The System submit the payment request to the financial institution
4) The System notifies the Costumer with a “Successful Payment”
5) The Use Case ends
Use Case Scenarios
A Scenarios is an complete path if execution through the entire use case
A scenario is a instance of the use case
Happy day scenarios is when it results in the successful realization of
the post condition (function)
An Exception Scenarios results in an exception state. The function is
not achieved
Use Case Flow versus Scenarios
Flow of a use case are like the network of roads connecting two cities
Scenarios of a use case are like the possible itineraries between two cities
Why do we need scenarios?
Ask Melanie
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