Log-in Abstract use case

General purpose: 

Log in the system


High / Focal role


The user is not currently logged in.


User intentions System responsabilities
1. User opens GMail main page  
  2. System shows sign in fields: username and password. It also shows an option to stay signed for following sessions.
3. User fills email and password  
  4. Open inbox folder



User is logged in; inbox folder is shown.


If email does not exist, or password is wrong, show an error message and stay at the same page.

If user selects the option to stay signed in, the browser should store the session for a time.