We have setup ejabberd on an Ubuntu server and we want to fetch all offline users in a room to send push notification.
How we can get them from database?
What will be configuration for it?
As defined in XEP-0045 MultiUser Chat, chat room in XMPP are presence-based. I means that to join a room you send a presence packet to the room. When you disconnect, the server sends a presence unavailable to the room so that you leave it. You can also send a presence unavailable to leave it "manually", but still stay connected.
It means that by definition, there is not offline users in an XMPP chat room.