As an IM system it shall support user to user communication

[greenlaw110]

1. Description

A logged in user shall be able to send message to another user (if permission granted).

Other requirements:

• The message shall be pushed to user agent if target user is online
• The message shall be archived in the system.
• The message shall be retrieved if user's agent request it
• The user agent shall acknowledge the message to be consumed once it received the message - do we really need it?

1.1 Implementation

A user-2-user message structure

• message body
  • should it support HTML code or markdown or other format?
  • how to encode the format?
• from user
• to user
• timestamp
• consumed flag - check if the message has been acknowleged by the user
  • do we really need it?

2. Acceptance criteria

1. Login user A
2. Send message to user B

If user B is online, the message shall be pushed to B's user agent. Otherwise, the message shall be pulled by user agent if B is online later