How are OCB "Extends" and "Includes" used?

In what direction do the “Extends” and “Includes” point to? I’m unsure.

E.g. for an example, I have a meta-model of a Capella deployment to help coordinate and at the same time demonstrate the benefits of the software.

Here I have an Operational Capability (OC) called “Develop the Solution” which involves Engineering, and another OC for “Achieve Business Goals” which involves many departments. I believe it’s an ‘Extends’ relationship, but does it point from the latter to the former OC?

Another example, I have an IT department OC called “Manage Backups” and below that are “Create Backups” and “Restore Backups”. I believe it’s an ‘Includes’ relationship, but if it is, which way does it point?

Hi @Epictetus

For Include vs Extend; I take the same definition and direction as is widely published in UML etc.

  • Extend relationship: The use case is optional and comes after the base use case. It is represented by a dashed arrow in the direction of the base use case with the notation <<extend>>.
  • Include relationship: The use case is mandatory and part of the base use case. It is represented by a dashed arrow in the direction of the included use case with the notation <<include>>.

Here are a few links to read:

Hope this helps, Josh

I believe that helps confirm my suspicions. In that case my “Develop the Solution” extends with some additional OC’s (e.g. Achieve Business Goals), pointing towards the base use case. And my “Manage Backups” includes some necessary OCs (Create Backups and Restore Backups), with the arrows pointing away from the base use case.

I do wonder still if it makes any difference to the model, in any way other than the appearance on this representation.

Except for “Notes”, everything you see in a Capella diagram has semantic meaning. In the case of your extends relation, it does create a relation in the model. If you right-click on your extends relation and select “Show in project Explorer”, you will see the model element it corresponds to in the model.
Stephane