Session-level messages communicate the state of the connection between a FIX client and TT FIX.
The following table describes the session-level FIX messages that TT FIX currently supports.
| Message | Purpose |
|---|---|
| Heartbeat (0) | Used to verify communication with TT FIX |
| Test Request (1) | Used to request a heartbeat |
| Resend Request (2) | Used to request a resend of a range of messages |
| Session-Level Reject (3) | Used to return the reason for rejecting an incoming message |
| Sequence Reset (4) | Used to reset the message sequence number or gap fill |
| Logon (A) | Used to establish a connection between a FIX client and TT FIX |
| Logout (5) | Used to terminate a connection between a FIX client and TT FIX |