Skip to content

FIX MESSAGE 35=A

Logon

MsgType (35) = ASessionAdded FIX.2.7

Definition

The logon message authenticates a user establishing a connection to a remote system. The logon message must be the first message sent by the application requesting to initiate a FIX session.

Message structure 66 distinct fields

Source order, including nested components and groups. Group counts precede the repeated entries. “Required here” is relative to the enclosing component or group, not unconditional in the message. A dash means not marked required; conditional requirements remain in the source notes. This is a reference, not a counterparty-specific validator.

  1. StandardHeaderComponentRequired

    MsgType = A

    1. 8 BeginStringStringRequired here

      FIX session profile (Always unencrypted, must be first field in message)

    2. 9 BodyLengthLengthRequired here

      (Always unencrypted, must be second field in message)

    3. 35 MsgTypeStringRequired here

      (Always unencrypted, must be third field in message)

    4. Indicates application version using a service pack identifier. The ApplVerID applies to a specific message occurrence.

    5. Used to support bilaterally agreed custom functionality

    6. 49 SenderCompIDStringRequired here

      (Always unencrypted)

    7. 56 TargetCompIDStringRequired here

      (Always unencrypted)

    8. Trading partner company ID used when sending messages via a third party (Can be embedded within encrypted data section.)

    9. Trading partner company ID used when sending messages via a third party (Can be embedded within encrypted data section.)

    10. 90 SecureDataLenDeprecated FIX.5.0SP2Length

      Required to identify length of encrypted section of message. (Always unencrypted)

    11. 91 SecureDataDeprecated FIX.5.0SP2data

      Required when message body is encrypted. Always immediately follows SecureDataLen field.

    12. 34 MsgSeqNumSeqNumRequired here

      (Can be embedded within encrypted data section.)

    13. (Can be embedded within encrypted data section.)

    14. Sender's LocationID (i.e. geographic location and/or desk) (Can be embedded within encrypted data section.)

    15. "ADMIN" reserved for administrative messages not intended for a specific user. (Can be embedded within encrypted data section.)

    16. Trading partner LocationID (i.e. geographic location and/or desk) (Can be embedded within encrypted data section.)

    17. Trading partner SubID used when delivering messages via a third party. (Can be embedded within encrypted data section.)

    18. Trading partner LocationID (i.e. geographic location and/or desk) used when delivering messages via a third party. (Can be embedded within encrypted data section.)

    19. Trading partner SubID used when delivering messages via a third party. (Can be embedded within encrypted data section.)

    20. Trading partner LocationID (i.e. geographic location and/or desk) used when delivering messages via a third party. (Can be embedded within encrypted data section.)

    21. 43 PossDupFlagBoolean

      Always required for retransmitted messages, whether prompted by the sending system or as the result of a resend request. (Can be embedded within encrypted data section.)

    22. 97 PossResendBoolean

      Required when message may be duplicate of another message sent under a different sequence number. (Can be embedded within encrypted data section.)

    23. 52 SendingTimeUTCTimestampRequired here

      (Can be embedded within encrypted data section.)

    24. 122 OrigSendingTimeUTCTimestamp

      Required for message resent as a result of a ResendRequest. If data is not available set to same value as SendingTime (Can be embedded within encrypted data section.)

    25. Required when specifying XmlData to identify the length of a XmlData message block. (Can be embedded within encrypted data section.)

    26. 213 XmlDataXMLData

      Can contain a XML formatted message block (e.g. FIXML). Always immediately follows XmlDataLen field. (Can be embedded within encrypted data section.)

      See Volume 1: FIXML Support

    27. Type of message encoding (non-ASCII characters) used in a message's "Encoded" fields. Required if any "Encoding" fields are used.

    28. The last MsgSeqNum value received by the FIX engine and processed by downstream application, such as trading system or order routing system. Can be specified on every message sent. Useful for detecting a backlog with a counterparty.

    29. HopGrpRepeating groupCount tag 627

      Number of repeating groups of historical "hop" information. Only applicable if OnBehalfOfCompID is used, however, its use is optional. Note that some market regulations or counterparties may require tracking of message hops.

      1. 627 NoHopsGroup count
      2. 628 HopCompIDString
      3. 629 HopSendingTimeUTCTimestamp
      4. 630 HopRefIDSeqNum
  2. 98 EncryptMethodintRequired

    (Always unencrypted)

  3. 108 HeartBtIntintRequired

    Note same value used by both sides

  4. Required for some authentication methods

  5. 96 RawDatadata

    Required for some authentication methods

  6. Indicates both sides of a FIX session should reset sequence numbers

  7. Optional, alternative via counterparty bi-lateral agreement message gap detection and recovery approach (see "Logon Message NextExpectedMsgSeqNum Processing" section)

  8. Can be used to specify the maximum number of bytes supported for messages received

  9. MsgTypeGrpRepeating groupCount tag 384
    1. 384 NoMsgTypesGroup count

      Specifies the number of repeating RefMsgTypes specified

    2. Specifies a specific, supported MsgType. Required if NoMsgTypes is > 0. Should be specified from the point of view of the sender of the Logon message

    3. Indicates direction (send vs. receive) of a supported MsgType. Required if NoMsgTypes is > 0. Should be specified from the point of view of the sender of the Logon message

    4. Specifies the service pack release being applied to an application message.

    5. Specified the extension pack being applied to a message.

    6. Specifies a custom extension to a message being applied at the session level.

    7. Indicates that this Application Version (RefApplVerID(1130), RefApplExtID(1406),RefCstmApplVerID(1131)) is the default for the RefMsgType(372) field.

  10. Can be used to specify that this FIX session will be sending and receiving "test" vs. "production" messages.

  11. 553 UsernameString
  12. 554 PasswordString

    Note: minimal security exists without transport-level encryption.

  13. Specifies a new password for the FIX Logon. The new password is used for subsequent logons.

  14. Encrypted new password- encrypted via the method specified in the field EncryptedPasswordMethod(1400)

  15. Session status at time of logon. Field is intended to be used when the logon is sent as an acknowledgement from acceptor of the FIX session.

  16. 1137 DefaultApplVerIDStringRequired

    The default version of FIX messages used in this session.

  17. The default extension pack for FIX messages used in this session

  18. The default custom application version (dictionary) for FIX messages used in this session

  19. 58 TextString

    Available to provide a response to logon when used as a logon acknowledgement from acceptor back to the logon initiator.

  20. Must be set if EncodedText field is specified and must immediately precede it.

  21. Encoded (non-ASCII characters) representation of the Text field in the encoded format specified via the MessageEncoding field.

  22. StandardTrailerComponentRequired
    1. 93 SignatureLengthDeprecated FIX.5.0SP2Length

      Required when trailer contains signature. Note: Not to be included within SecureData field

    2. 89 SignatureDeprecated FIX.5.0SP2data

      Note: Not to be included within SecureData field

    3. 10 CheckSumStringRequired here

      (Always unencrypted, always last field in message)