FIX services are available 24/7 except during software deployments, which occur Friday evenings approximately every two weeks for UAT environments and monthly for Production environments.
TT FIX Order Routing sessions are persistent by default and reset on Saturdays at 22:00 UTC.
Clients may optionally define a custom daily reset time when configuring a FIX Order Routing session in Setup [link to the Creating FIX Session in Setup section]. The default reset on Saturday at 22:00 UTC will occur in addition to a custom reset schedule defined on the session.
Note If a FIX client remains connected to a FIX session when either the default or custom scheduled reset time occurs, TT’s FIX engine will send a Logout message.
By default, message sequence numbers for FIX sessions are reset when TT resets all FIX sessions. Message sequence numbers can also be reset, when desired, by setting Tag 34 (MsgSeqNum) = 1 and Tag 141 (ResetSeqNumFlag) = Y when sending a Logon (A) message.
TT FIX will ensure ClOrdID (tag 11) uniqueness for:
For more information, refer to the ClOrdID tag description in the New Order Single (D) message.
If your FIX client application disconnects and subsequently reconnects, TT’s FIX engine will perform an internal recovery process to query our cloud based order book database and will deliver all unsent execution reports by applying an incremental sequence number that picks up where we left off prior to the disconnect. The session recovery process can be considered complete in all cases with a News message [35=B].
This eliminates the requirement for your FIX client application to detect a gap on the session level and request missed execution reports while disconnected. This also allows FIX client applications to failover seamlessly into a different datacenter without sequence number consideration.
If your FIX client application disconnects and was unable to process executions prior to the disconnect, TT’s FIX engine supports the standard message replay mechanism specified by the FIX Protocol by honoring Resend Request  messages received from FIX client applications.
In extreme cases where your FIX client application unexpectedly disconnected and required intervention on your side to reset sequence numbers that resulted in a subsequent Logon with 141=Y and 34=1, TT’s FIX engine will still perform a session recovery process that will query our cloud based order book database for executions marked as undelivered and apply an incremental sequence number to each message message. In this case, Logon [34=1], missed executions [34=2, 3, etc]. The session recovery process can be considered complete in all cases with a News message [35=B].
In the scenario where although TT delivered all relevant execution reports to your FIX client application, your internal system may have experienced an issue and was unable to process the messaging. TT’s FIX Engine is aware of sent messages, but we are unaware of your application's success or failure to process them. If your FIX client application also required a sequence number reset and cannot request a Resend Request  message, executions can be retrieved through our REST API [link to REST].
In order to add support CME Drop Copy 4.0 in the TT Inbound Drop Copy service, tags 5024 and 5979 have been added to the TT XML schema Service as shown:
<field number='5024' name='StartSequenceNumber' type='SEQNUM' />
<field number='5979' name='RequestTime' type='STRING' />
These tags will not appear in any messages used by TT standard outbound drop copy service or any other customer-facing FIX interfaces.
No customer action is required regarding these tags.
The FIX schema now includes the optional FIX Tag 18001. This optional tag is available in all order and execution report messages. In addition, these tags will not appear in any current messages in production and are reserved for future use.
FIX Order router now routes "Instrument Not Found" rejects to the Drop Copy session. The message appears in Tag 58 (Text) and includes the instrument lookup field (e.g., instrument_id, Name, Alias, RIC_Code, ect.) and value.
If a valid account and user exist on the order, the FIX Order Router will use those values, otherwise, it will use the Error Account + default user.
The IFOA mitigation system does the following: