UML Use Case Diagram

A UML use case diagram is a specification for how an actor should complete a set goal when interacting with a system.

Example

actor "Student" as a1
 
package College {
  usecase "Study" as g1
  usecase "Go to lecture" as g2
  usecase "Read book" as g3
}
 
a1 --> g1
a1 --> g2
a1 --> g3

This is an example College system in which the Student actor can perform some common actions undertaken to achieve goals at a College

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Textual Descriptions

A UML use case diagram must come pared with a matching textual description of the format:

Heading	Expected Value
Participating Actor/s	Any actors involved with the use case
Entry Condition	How the process interacted with begins
Exit Condition	How the process interacted with finishes
Normal Scenario	What the success path looks like for the use case
Error Scenario	What a scenario in which an error occurs would look like

Example

For the system in the previous example, a textual description might look like:

Heading	Result
Participating Actor	Student
Entry Condition	The student opens their book to begin to study
Exit Condition	The student closes their book having finished studying
Normal Scenario	The student successfully retains all the information they look over
Error Scenario	The student gets distracted by Instagram reels