问题
iam going to design a system that has a login facility. After login the logged user can do several things so is it needs to include login usecase by that several usecases.
回答1:
In most cases, it will only clutter up your diagrams. Login is neither complex nor does it give you much added value as a use case. In your textual document that includes the use cases with description, include as a prerequisite a list of features that require a successful login. Easier to track and to test.
来源：https://stackoverflow.com/questions/19443682/is-it-necessary-to-include-the-login-for-every-usecase