I am new to the open fire.
What is the room concept in the open fire?
If the user goes offline then the user is kicked off from the Room.
Is there any way to stay offline users in the room instead of they kicked off from the room when users go offline or terminate the application?
A chat occupant is someone that is online. People can retain group membership, even if they are offline. Those people won’t automatically receive messages that are exchanged in the group though. Typically, their clients will retrieve messages from a message archive when they rejoin the room. Openfire supports message archiving using its Monitoring Service plugin.