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The MFAPI Client initiates a new session with a Logon message - this populating NextExpectedMsgSeqNum[789] which contains the next MsgSeqNum[34] value msgSeqNum value that the Client expects to receive from the Whisperer Feed Handler. 

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• If the Client is expecting a sequence number higher than the FH's next-to-be-assigned msgSeqNum, then this is an unrecoverable error and the FH will abort the session with a Logout message (using it's next sequence number).

  Tip
  The Customer should contact MF Support to agree the correct resolution actions.

• Otherwise the FH will issue a LogonResponse message containing the next MsgSeqNum[34] value that it expects to receive from the Client.

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• If the Client is expecting a sequence number lower than the FH's next-to-be-assigned msgSeqNum

[34]

• (as used in the preceding Logon response), then the message gap is resolved by the FH with SequenceResetGapFill messages and/or the resending of persisted messages as necessary. 

  Warning

  Should a Client specify a next-expected inbound sequence number too low (e.g. expecting '1' on re-logon just prior to weekly trading session close), then the FH will service most of the range to correct with a SequenceResetGapFill. For the more recent messages that are still persisted, these will be processed as normal. The FH will not resend a week's worth of persisted messages. Refer to Whisperer Enterprise - Session Management above

more more detail.

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• for more detail.

   Resent messages are characterised by: 

• • Msg.messageHeader.msgSeqNum populated with the original sequence number
  • Msg.messageHeader.sendingTime populated with the resend time
  • Msg.TradingFlags.PossDupFlag = TRUE
  • Msg.OrigSendingTime populated with Msg.messageHeader.sendingTime of original message

• The FH will then issue a LogonResponse message - populating NextExpectedMsgSeqNum[789] which contains the next msgSeqNum value that it expects to receive from the Client.

• The Whisperer Feed Handler signals it's completion of session synchronisation with a TestRequest. 

  Note
  Any new (i.e. not SequenceResetGapFill or resent) messages sent by the MFAPI Client prior to the required Heartbeat response will result in ErrorReport messages.

  
  

• After any inbound sequence number gaps have been resolved for the MFAPI Client ,

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• the Client then reciprocates in a similar manner, based on the the next

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• msgSeqNum value that the Whisperer Feed Handler expects to receive from the Client - as specified in it's LogonResponse. The Whisperer Client signals it's completion of session synchronisation with a TestRequest.

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Logout

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The recipient of a Logout message must echo it with a LogoutResponse (using it's next sequence number).

• It is the responsibility of the Logout initiator to terminate the socket connection on receipt of the

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• LogoutResponse.
• If no LogoutResponse is received within HeartBtInt + MaxTx seconds of the issuance of the Logout, then the session and associated TCP socket connection must be dropped.

ErrorReport

The ErrorReport is a custom, user-defined, message used by the Whisperer Feed Handler to notify the Client when erroneous messages are received:

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