Writing valid use cases Reading Notes (10) -- connection Use Cases

1 Sub-Use Cases: A execution step can be the name of a simple step or another use case.

Generally, if the steps are marked with underscores (_) or simplified Chinese characters, this step is a sub-use case,UMLThe Use Case graph is represented by<Include>To indicate

2, Extended use cases

Another connection is required between two use cases, which is similar to an extension mechanism. It has the following features:

(1)There is a primary activity that can be interrupted

(2)The main activity can be interrupted in multiple ways and cannot be controlled.

You can consider using the same extension mechanism as the description scenario, but here is the creation of a new use case. The new use case is called an extended use case (Extension use caseIn addition to independent use cases, it is the same as scenario extension. An extension case starts with a condition and is referenced where the condition may be met in the base case. All conditions should be placed in the trigger event section of the template. See the following example.

Use Case: Edit document

Primary performer: User Range:Wapp Level: User target Trigger event: The user opens the applicationProgram Prerequisites: None Main success scenario: 1.UserOpen and edit a document 2.UserEnter or modify text ...... ...... UserSave documentAnd exit the application.

Use Case: check spelling

Primary performer: User Range:Wapp Level: Sub-function! Prerequisites: A document is opened. Trigger event:When the document is opened and the user chooses to open the spelling check programEdit documentAt any time. Main success scenario: ...... Wait ......

Note that the Italic part of the "check spelling" use case is not mentioned in the base case (edit document use case, however, when checking spelling cases, you can write trigger events to introduce the base case. The base case does not depend on the extension case, which is flexible for future expansion. However, the extension case depends on the base case, if the base case changes, the extended case may be affected.

3Create extension cases only when necessary. The first case is that when many users may use Asynchronous services or interrupt services, these services should not affect the basic use cases. Another scenario is when you write additional documents for a locked requirement document. Expansion is fragile when the base case is not locked.

 

This chapter describes UML include and extend link.