How to model dependencies between components in a lower level view

Question

I have a component diagram (level 1) with dependencies between the internal components. The Account component "uses" the Billing component:

Now I want to create a level 2 diagram of the Account component. How do I model the "usage" dependency between Account and Billing (now outside of the view)? Should I create a port? Is it ok to omit it completely?

Answer 1

From the UML standard, all three options are allowed:

1. Omit Billing completely.
2. Show Billing outside of Account and have a «use» relationship directly from one of the inner components to Billing.
3. Show Billing outside of Account and connect it via a port and an interface.

Which option you choose is highly subjective.

Here are some considerations:

1. Use option 1 if the connection with Billing is not something you want to convey to the reader in this diagram.
2. Use option 2 if the name of the interface via which the connection with Billing is made is too much detail to show in this diagram.
3. Use option 3 otherwise.