Recommended Login - Unitized Port (BZX Only)
Request a replay of everything that you missed.
The login protocol supports a variety of options for how a member may want to approach reconciling sequence numbers and messages after a disconnection. For most members, the following Login strategy is the simplest approach to support a robust, lossless login experience.
Unlike convenience ports, a unitized port is capable of replaying a limited window of messages for the port. If the number of messages needed exceeds the available window, the login will be rejected with LoginResponseStatus = R (replay too deep). In such cases, members may either elect skip undelivered messages (see No Replay) or use a deep replay strategy (see Deep Replay - Unitized (BZX Only)).
| Field Name | Value | Comment |
|---|---|---|
| StartOfMessage | BO E3 | |
| MessageLength | 20 00 | 32 |
| MessageType | 01 00 | 1 (login request) |
| MatchingUnit | 00 | |
| Reserved | 00 | |
| SequenceNumber | 00 | (unsequenced) |
| SessionId | 41 42 43 44 | (ex. "ABCD") - Session Id as supplied by Cboe |
| SessionSubId | 30 30 30 31 | (ex. "0001") Session Sub Id as supplied by Cboe |
| Password |
| (ex. "abcdefghij") Password |
| ReplayInstruction | 52 | R - Replay unknown units. |
| NumberOfUnits | 01 | The single unit for the unitized port is specified |
| →UnitNumber | 03 | Matching unit #3 |
| →UnitSequence | 00 00 00 00 | Last SequenceNumber that member received with MatchingUnit=3. Zero if member has not received anything for MatchingUnit=3, for instance as the first login of the day. |