John Hofman US001

User Story

Chris starts up the IM program. He is prompted to input a unique username and to login. When he has logged in he can see a list of the other users online. Seeing that Joe is online he starts a chat by selecting Joe in the online user list and writing a message. Chris's message appears in a new chat. Joe responds with a message and it appears in the chat also. Chris decides to stop chatting and exits the chat, he then logs off and closes the program.

Behind the Scenes

When Chris logs on, the IM client checks the uniqueness of his username with the server (against the list of online users). Chris' username is unique so he is logged on and added to the online list. Chris' client is then updated with the current list of online users so that Chris can see them. When Chris starts a chat with Joe the client registers the chat with the server and passes the message. When Joe replies the server passes the message to Chris' client so that it can be added to the chat

Notes

• There are users, chats and messages
• Users:
  • Users have unique usernames
  • Users can 'login/logout and have state (logged in/out)
  • Users can be invited to or leave chats
  • Users can write a message to a chat
• Chats:
  • Chats are started by a user by sending messages to a user
  • Chats have a history of messages