UML Expanded Use Case

A UML expanded essential use case is a more detailed description of the processes used to accomplish the system function. An expanded use case is built upon a high level use case. There are two sections to the high level use case which are a heading and a body. The heading describes the name, actors, description, type of use case, and more. The body describes typical events and alternatives to the typical events. This includes two or more columns with an actor action in one column and the system response in the other column. Typical events will happen 80% or more of the time and alternatives will happen only 20% or less of the time.

  • Name of the process.
  • The actors involved with the initiating actor defined.
  • The description of the process from the high level use case.
  • Type of use case such as primary/secondary, essential/real. Normally this is "primary, essential".
  • Cross references - Reference any related system functions or use cases.
  • Preconditions - Conditions that must be true before the use case can happen.

Syntax

Name: SystemAction

Actors: Person1 (Initiator), Person2, OtherSystem

Description: The use case begins when Person1 arrives at the system with items and...

Type: primary, essential

Cross references: System function1

Preconditions: Resources must be available.

Actor ActionSystem Response
Typical Events:
1.
2.
3.
Alternatives:
1.

One step in the course of events is not normally categorized as a use case.