Anytime you're interacting with the database, you'll need to use database keys. Anytime you're interacting at the API interface level, you'll need URLs. Anythin

Anytime you're interacting with the database, you'll need to use database keys. Anytime you're interacting at the API interface level, you'll need URLs. Anything in the middle is then going to be a gray area, especially when you have multiple people working on this implementation together.