Use Case Diagram

Use Case Diagram
Actor
Relationship
Primary Actor
Supporting Actor
<<include>>
<<extend>>
Use Case
Naming Use Case
Start out with a verb, followed by a noun
Use present tense for verb, do not use continuous tense
Identify Use Case
What can the system do?
What does the actor want the system to do?
Generalization
One actor can participate in all the associations with use cases that the more general actor can, plus some additional use cases
One use case provides all the functionality of the more general use case, and some additional functionality
Use Case Descriptions
Input
Output
Recorded
Conditions
Prototype
Used to help elicit requirements
Used to test out the system architectures for non-functional requirements
Show how the user interface will look like for the client
Questions to find primary actor
Who uses the system?
Who maintains the system?
Who owns the system?
How to find supporting actor
What other system is the system using?
Include the behaviour of one use case into the flow of another use case
Do not create a hierarchical functional decomposition of the system by splitting a use case into several use cases
Provides a way to insert new behaviour into an existing use case
Generally not a complete use case, therefore it cannot be triggered by an actor
You can choose whether or not to execute the extension use case
Purpose
Provide an overview of all or part of the usage requirements for a system
Helps communicate the scope of a project
Helps model the analysis of usage requirements in the form of a system use-case model
Stakeholders who trigger the use case or cause the use case to be executed
Actor that interacts with the use case after it has been triggered
A role that some external entity adopts when interacting with the system DIRECTLY
Something that an actor wants the system to do
A simple paragraph to describe what the use case does
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