Name: Yash Pitre
Roll No: 30
Date: 09-02-2021
Question 1: What is Extension Point in Use case. Explain with an Example?
In UML models, an extension point identifies the point in the base use case where the
behaviour of an extension use case can be inserted. The extension point is specified for a base use
case and is referenced by an extend relationship between the base use case and the extension use
case. A base use case can have several extension points.
Each extension point has a unique name that identifies one or several locations in the
behaviour sequence of the base use case. Extension points may be shown in a compartment of the
use case oval symbol under the heading extension points. Each extension point must have a name,
unique within a use case. Extension points are shown as a text string according to the syntax:
extension point ::= name [: explanation ]
The optional explanation is some description usually given as informal text. It could be in
other forms, such as the name of a state in a state machine, an activity in an activity diagram, some
precondition or postcondition.
Registration use case with extension points
Registration Help and User Agreement
Extension points may be shown in a compartment of the use case rectangle with ellipse icon under
the heading extension points.
Registration use case is conditionally extended by Get Help On Registration
use case in extension point Registration Help.
K.J. SIM
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