The consequences of a server or broker failure in an (HTTP or HTTPS) connection vary depending on the specific component that has failed:
If the application server or Web server fails and is restarted, all existing connections are restored with no effect on clients.
If the broker fails and is restarted, an exception is thrown and clients must reestablish their connections.
In the unlikely event that both the broker and the application server or Web server fail and the broker is not restarted, the application server or Web server will restore client connections and continue waiting for a broker connection without notifying clients. To avoid this situation, always restart the broker after a failure.