UML Use case Specification for an Extended Use Case

Question

I'm documentating a design, I have a doubt. The Use Case Specification RUP template have an extensión point section, and I was wondering if this section was meant to describe the extended use case or as I suppossed first, I have to make a specification of its own.

Someone please clarify this for me. Thanks in advance.

Answer 1

Please see this answer to understand what is an extended UC.

UML, include, extend relationship

Extension point is defined in the extended UC and specifies how/when exactly the extending UC can be invoked. As a UC is typically described by scenarios and scenarios have steps, you usually describe the extension point as steps in which the extension can occur.

In the example I gave you, "Place order" is the extended UC and "Print Order" is the extending UC.

Let's suppose the following scenario of the "Place Order": 1. User fills the form 2. User confirms the input 3. System validates the input 4. If ok, System registers the Order 5. If ok, System displays the confirmation message

• Extension point might be defined for the step 5 (only successfull Order can be printed).
• Alternativelly it can be defined for the range of steps between 2-5 (Order might be in the DRAFT or COMPLETED state)

Another nice way to specify extension points is via activity diagram (if you want to avoid textual scenario descriptions).