Session message list
| Message | MsgType (35) | Direction | Purpose |
|---|---|---|---|
| Logon | A | Client to service; service to client | Opens a FIX session and negotiates heartbeat and sequence behavior. |
| Heartbeat | 0 | Both directions | Confirms that the FIX connection is alive. |
| TestRequest | 1 | Both directions | Requests an immediate heartbeat response when a peer appears idle. |
| ResendRequest | 2 | Both directions | Requests retransmission for a missing sequence range. |
| Reject | 3 | Service to client | Rejects a session-level message or invalid session condition. |
| SequenceReset | 4 | Both directions | Advances sequence state or fills gaps for messages that are not resent. |
| Logout | 5 | Both directions | Closes the FIX session or reports a session condition that requires disconnect. |
Logon fields
Logon (35=A) opens a session.
| Tag | Name | Req | Type | Description |
|---|---|---|---|---|
98 | EncryptMethod | Y | Int | Encryption method. Use 0 for none unless a different value is assigned for the session. |
108 | HeartBtInt | Y | Int | Heartbeat interval in seconds. Must be greater than 15 and less than 100. |
141 | ResetSeqNumFlag | N | Boolean | Y resets sequence numbers for the session. N continues the previous sequence state. |
Heartbeat fields
Heartbeat (35=0) contains no required body fields in this contract.
When replying to TestRequest (35=1), include the received TestReqID (112).
Test request fields
| Tag | Name | Req | Type | Description |
|---|---|---|---|---|
112 | TestReqID | Y | String | Identifier that the peer echoes in the heartbeat response. |
Resend request fields
| Tag | Name | Req | Type | Description |
|---|---|---|---|---|
7 | BeginSeqNo | Y | Int | First sequence number requested. |
16 | EndSeqNo | Y | Int | Last sequence number requested. Use 0 to request all messages from BeginSeqNo (7) onward. |
Reject fields
| Tag | Name | Req | Type | Description |
|---|---|---|---|---|
45 | RefSeqNum | Y | Int | Sequence number of the rejected message. |
58 | Text | N | String | Human-readable reject detail. |
371 | RefTagID | N | Int | FIX tag that caused the reject, when applicable. |
372 | RefMsgType | Y | String | MsgType (35) of the rejected message. |
373 | SessionRejectReason | N | Int | FIX session reject reason code. |
Sequence reset fields
| Tag | Name | Req | Type | Description |
|---|---|---|---|---|
36 | NewSeqNo | Y | Int | Next sequence number expected after the reset or gap fill. |
123 | GapFillFlag | N | Boolean | Y indicates a gap fill. Omitted or N indicates a sequence reset. |
Logout fields
| Tag | Name | Req | Type | Description |
|---|---|---|---|---|
58 | Text | N | String | Logout detail. If the value states MsgSeqNum too low, expecting X but received Y, relogon with MsgSeqNum (34)=X. |