The following use case diagram shows the requirement for Tweety:

The actor is the User of the Tweety application. It has the following use cases:

• Login: This use case is required to authenticate users so that each user can be uniquely identified, to allow only authenticated users to perform actions.
• List Tweet: This use case is where a user can list all the tweets available for that user. It requires the user to be authenticated.
• Reply Tweet: This use case is where a user can reply to a Tweet. It requires the user to be authenticated.
• Send Tweet: This use case is where a user can send a Tweet. It requires the user to be authenticated.
• Follow User: This use case is where a user can follow another user. It requires the user to be authenticated.
• View Profile: This use case is where a user's profile can be viewed by another. It requires the user to be authenticated.
• Logout: This use case is where a logged in user can log out.