The protocol is binary and uses 32-bit integers with network byte order, where applicable. Login sequence is character-based. Login HTTP server always acts as the server, user process module always acts as the client in the login procedure.
Client authenticates to the server.
General format of the message is the same as used in FTP protocol, so message identification by the client should be performed by the numeric response code. All other responses are negative. Otherwise, skips to the step 7. Login sequence may fail because of wrong username, password, application name, mismatched username and application name, application instances limit and internal error. Failure causes client to be disconnected.