Communication is made via the HTTPS protocol, which runs on standardised port 443. Authentication requires login and password data to be transmitted in the first connection. Subsequently, the server returns the client a cookie with a session key for further requests. Having failed to send more requests within a timeout (20 minutes at present), the client will be logged out automatically. The next requests will thus return the HTTP return code 401 (Not authorised). Then the client has to log in again.