The use case diagram 

The following use case diagram shows the requirement for the dashboard, which is nicknamed Retro Board:

The actor is a User of the Retro Board and is a team member who is involved in a sprint. It has the following use cases:

1. Login: This is required to authenticate users so that each comment can be uniquely identified
2. Post Comments: This is where a logged in user can post their comment under its respective type so that it will be recorded for later, and also collaborate with other users in real time
3. View Comments: This is where a logged in user can view comments made by all users

All actions need authentication and authorization to distinguish users and relate the comments they make. All comments need to be saved based on the date when they were made and should be retrievable based on the date also.