CODEWITHSUNDEEP
includeumlextenduse-case
Visuddha Karunaratne
Visuddha Karunaratne

Reputation: 536

Use case diagrams use of <<extend>>

in my system "compare modifications" and "save image" are optional activities. but they are presented to the user. user may or may not use them. is this the correct form showing the scenario in use case diagram? Imstill new to UML , if I'mnot wrong i think extend keyword can be used to show optional activities.

enter image description here

Upvotes: 1

Views: 2020

Answers (3)

Darren Burgess
Darren Burgess

Reputation: 4312

In the most simple terms Includes is something which is mandatory and Extends is optional, this is a very simple explanation which helped me understand.

Upvotes: 0

Hari Subramaniam
Hari Subramaniam

Reputation: 1876

Are Save Image and Compare Modifications separate use cases? If they are i wonder what user scenario they describe?Too generic IMHO. But i dont know the domain under study so cant really drive my point there. Extend is applied to scenarios where extending use cases are specialized versions of the parent use cases. So to translate that into your scenario, whenever the actor encounters Save Image functionality(assuming Save Image has some real business functionality rather than just a Save Image screen) he might choose to Store the image to disk(and thereby execute Store Image to Disk's Normal Flow, Alternative flow,BRs etc) or he might not, in which case the flow might continue with Save Image use case's Alternative Flow(AFs). If my assumptions are right, then the answer to your questions is YES.

Upvotes: 1

vainolo
vainolo

Reputation: 6987

<<extend>> use cases are used when you want to provide point in a use case where you can later add new functionality, and not to show optional operations. Any use case can be optional, they only show functionality that the system provides to the user and do not show ordering or causality. The <<include>> use cases do show some causality relation but this is also minor and nor compulsory.

Upvotes: 1

Related Questions