Hi Keerthana, the pusher module gives you the tools to trigger a microflow from server to client in Mendix. This means the end-user does not need to click a button to update the screen or show a message, which you would normally do.
For this to work you need a pusher account and setup your api keys onthe pusher website. Once that is done you use the Notify action to send the event and make use of the Listen widgets to trigger what to do when event is received.
In example: End-user is writing message, then you send the Notify action. Then Listen widget trigger microflow and message is retrieved from database.
Thus pusher is only the mechanism to send the event and trigger what to do when event is received. You need to build the features yourself. And the chat message that end-user sends to another is not send to pusher okay!
Hope this helps.