handling online transactions in a use case diagram

Question

I have to design a use case diagram for a video rental store.In this the customers should be able to pay rental fees online.In this sort of a situation when online payments have to be done, does the bank become an actor?Would the tasks of the bank be:

• verify credit card number
• make transaction

And in the system should there be an actor as a process system which has the tasks of:

• accept order information from customer
• send verification details to the bank(requseting to verify credit card no., amount of the order etc)
• send confirmation details to the buyer(whether the card,the amount is approved by the bank or declined)

Should these tasks and actors need to be included in a video rental or any other system which uses online payments or is this unnecessary?

Answer 1

If the bank is external to the system under design, which I assume for a video store, yes, it will be an actor.
Hint: Stick with the term "use case" instead of "task".
You can make them as fine grained as you like depending on what you want to convey. Keep in mind that normally, it's good practice to make them not too detailed. You want to give no more than an overview. Plus you don't really know what's behind the facade of the bank's API, so don't dig deeper than your API calls.