Logout Message Fields
A Logout message is usually sent in response to a Logout Request message. Any queued data is transmitted, a Logout message is sent, and Cboe will close the connection. However, a Logout message may also be sent if the Member violates the protocol specification (e.g., by moving backwards in sequence number).
The Logout message contains the last transmitted sequence number for each unit, allowing the Member to check that their last received sequence number matches.
| Field | Offset | Length | Data Type | Description |
|---|---|---|---|---|
| StartOfMessage | 0 | 2 | Binary | Must be 0xBA 0xBA. |
| MessageLength | 2 | 2 | Binary | Number of bytes for the message, including this field but not including the two bytes for the StartOfMessage field. |
| MessageType | 4 | 1 | Binary | 0x08 |
| MatchingUnit | 5 | 1 | Binary | Always 0 for session level messages. |
| SequenceNumber | 6 | 4 | Binary | Always 0 for session level messages. |
| LogoutReason | 10 | 1 | Alphanumeric |
|
| LogoutReasonText | 11 | 60 | Text | Human-readable text with additional information about the reason for logout. Particularly useful if LogoutReason = ! (Protocol Violation). |
| LastReceived SequenceNumber | 71 | 4 | Binary | Last inbound (Member to Cboe) message sequence number processed by Cboe. |
| NumberOfUnits | 75 | 1 | Binary | A number, n (possibly 0), of unit/sequence pairs to follow, one per unit from which the client has received messages. |
| UnitNumber 1 | 1 | Binary | A unit number. | |
| UnitSequence1 | 4 | Binary | Highest available sequence number for the unit. | |
| … | ||||
| UnitNumber n | 1 | Binary | A unit number. | |
| UnitSequencen | 4 | Binary | Highest available sequence number for the unit. |
| Field Name | Hexadecimal | Notes |
|---|---|---|
| StartOfMessage | BA BA | Start of message bytes. |
| MessageLength | 55 00 | 85 bytes |
| MessageType | 08 | Logout |
| MatchingUnit | 00 | Always 0 for session level messages |
| SequenceNumber | 00 00 00 00 | Always 0 for session level messages |
| LogoutReason | 55 | U = User Requested |
| LogoutReasonText | 55 73 65 72 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 | User |
| LastReceived | 54 5A 02 00 | Last Cboe received sequence of 150,100 |
| SequenceNumber | ||
| NumberOfUnits | 03 | Two unit/sequence pairs to follow; |
| UnitNumber1 | 01 | Unit 1 |
| UnitSequence1 | 4A BB 01 00 | Last sent sequence of 113,482 |
| UnitNumber2 | 02 | Unit 2 |
| UnitSequence2 | 00 00 00 00 | Last sent sequence of 0 |
| UnitNumber3 | 04 | Unit 2 |
| UnitSequence3 | 79 A1 00 00 | Last sent sequence of 41,337 |