Use Case Modeling

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Use Case Modeling

• ECE 621

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UC Modeling and QFD

• Another excellent method of eliciting the
  functional requirements for a system
• UC modeling is used mainly in Object-Oriented
  projects

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What will it be used for?

• For your customers
• Customers verify that this is the system they
  want
• For you designers
• What is the problem exactly, so we can design a
  solution for it?
• For your testers
• We know exactly what to test for

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• For your maintenance team
• Helps the maintenance team understand the code
• For you
• Acquiring an in demand skill that deals with
  higher levels of management than coders do
• Higher level of management -gt more money ?

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What are UC models made of?

• Two major components
• UC Diagram Presents a visual summary of the
  services offered by the system to its users
• UC Descriptions A map of scenarios existing
  between users and the system

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Example of a Use Case
Rent Video
Just a visual summary. Tells you a lot, but not a
whole lot.
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Use Case Descriptions

• Diagrams are nice, but they are not enough
• How does the customer rent the video?
• What does he/she need to do?
• Just what happens exactly?
• Every use case must be accompanied by a textual
  description
• Every actor must be accompanied by a textual
  description

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Rent Video UC Description

• The Customer starts the use case when he/she
  wants to rent a video. The Customer providers
  his/her membership card. The system verifies that
  the Customer does not have any due charger. The
  system then adds the selected video to that
  Customers account and computes the due date. The
  Customers account is charged.

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Use Case modeling issues

• Inconsistency
• UC descriptions do not conform to the diagram
• UC descriptions are conflicting
• Correctness
• Wrong information
• Not Analytical
• Premature design decisions
• Understandability