Heartbeats

Client Heartbeat messages are sent from Member to Cboe and Server Heartbeat messages are sent from Cboe to Member if no other data has been sent in that direction for one second. Like other session level messages, heartbeats from Cboe to the Member do not increment the sequence number. If Cboe receives no inbound data or heartbeats for 5 seconds, a Logout message will be sent and the connection will be terminated. Members are encouraged to have a one second heartbeat interval and to perform similar connection staleness logic.