1) Arrows indicate logical
associations, not software messages.
Arrows can go in one or both directions between different types of
objects. Don’t worry too much about
arrows or the direction of the arrows.
2) There should be a small number of
controllers (e.g., between two and five) per average use case. If you have only one controller per use case,
you’re likely to have a lot of very small user cases. If you have more than 10 controllers,
consider splitting the use case.