OnixS
Dictionary icon

FIXT 1.1: Session Protocol – FIX Dictionary

Messages by MsgType | Messages by Name | Fields by Tag | Fields by Name | FIXT 1.1 | Home

FIX Session-level Test Cases and Expected Behaviors

 

Introduction

These test cases are from the perspective of the FIX system being tested. The FIX system receives the "Condition/Stimulus" and is expected to take the appropriate action as defined by "Expected Behavior".

 Buyside-oriented (session initiator) Logon and session initiation test case
Ref ID Pre-condition Test case Mandatory/Optional Condition/Stimulus Expected Behavior
1B   Connect and send Logon<A> message Mandatory a. Establish Network connection Successfully open TCP socket with counterparty
b. Send Logon<A> message Send Logon<A> message
c. Valid Logon<A> message as response is received If MsgSeqNum is too high then send ResendRequest<2>
d. Invalid Logon<A> message is received
  1. Generate an "error" condition in test output
  2. (Optional) Send Reject<3> message with RefSeqNum(45) referencing Logon<A> message’s MsgSeqNum and where Text(58) references error condition
  3. Send Logout<5> message with Text(58) referencing error condition
  4. Disconnect
e. Receive any message other than a Logon<A> message
  1. Log an error “first message not a logon”
  2. (Optional) Send Reject<3> message with RefSeqNum(45) referencing Logon message’s MsgSeqNum and where Text(58) references error condition
  3. Send Logout<5> message with Text(58) referencing error condition
  4. Disconnect


 Sellside-oriented (session acceptor) Logon and session initiation test case
Ref ID Pre-condition Test case Mandatory/Optional Condition/Stimulus Expected Behavior
1S   Receive Logon<A> message Mandatory a. Valid Logon<A> message
  1. Respond with Logon<A> response message
  2. If MsgSeqNum(34) is too high then send ResendRequest<2>
b. Logon<A> message received with duplicate identity (i.e. same IP, port, SenderCompID, TargetCompID, etc. as existing connection)
  1. Generate an "error" condition in test output
  2. Disconnect without sending a message (note sending a Reject<3> or Logout would consume a MsgSeqNum)
c. Logon<A> message received with unauthenticated/non-configured identity (i.e. invalid SenderCompID, invalid TargetCompID, invalid source IP address, etc. vs. system configuration)
  1. Generate an "error" condition in test output
  2. Disconnect without sending a message (note sending a Reject<3> or Logon<5> would consume a MsgSeqNum)
d. Invalid Logon<A> message
  1. Generate an "error" condition in test output
  2. (Optional) Send Reject<3> message with RefSeqNum(45) referencing Logon<A> message’s MsgSeqNum and with Text(58) referencing error condition
  3. Send Logout<5> message with Text(58) referencing error condition
  4. Disconnect
Receive any message other than a Logon<A> message Mandatory First message received is not a Logon<A> message.
  1. Log an error “first message not a logon”
  2. Disconnect


 Test cases applicable to all FIX systems
Ref ID Pre-condition Test case Mandatory/Optional Condition/Stimulus Expected Behavior
2   Receive Message Standard Header Mandatory a. MsgSeqNum(34) received as expected Accept MsgSeqNum for the message
b. MsgSeqNum(34) higher than expected Respond with Resend Request<2> message
c. MsgSeqNum(34) lower than expected without PossDupFlag(43) set to Y

Exception: SeqReset-Reset
  1. Whenever possible it is recommended that FIX engine attempt to send a Logout message with a text message of "MsgSeqNum too low, expecting X but received Y"
  2. (optional) Wait for Logout message response (note likely will have inaccurate MsgSeqNum) or wait 2 seconds whichever comes first
  3. Disconnect
  4. Generate an "error" condition in test output
d. Garbled message received
  1. Consider garbled and ignore message (do not increment inbound MsgSeqNum) and continue accepting messages
  2. Generate a "warning" condition in test output

e. PossDupFlag(43) set to Y; OrigSendingTime(122) specified is less than or equal to SendingTime(52) and MsgSeqNum(34) lower than expected

Note: OrigSendingTime should be earlier than SendingTime unless the message is being resent within the same second during which it was sent
  1. Check to see if MsgSeqNum has already been received
  2. If already received then ignore the message, otherwise accept and process the message

f. PossDupFlag(43) set to Y; OrigSendingTime(122) specified is greater than SendingTime(52) and MsgSeqNum(34) as expected

Note: OrigSendingTime should be earlier than SendingTime unless the message is being resent within the same second during which it was sent
  1. Send Reject<3> (session-level) message referencing inaccurate SendingTime (≥ FIX 4.2: SessionRejectReason(373) = 10 - "SendingTime accuracy problem")
  2. Increment inbound MsgSeqNum
  3. Optional:
    • Send Logout<5> message referencing inaccurate SendingTime value
    • (optional) Wait for Logout<5> message response (note likely will have inaccurate SendingTime) or wait 2 seconds whichever comes first
    • Disconnect

Generate an "error" condition in test output.

g. PossDupFlag(43) set to Y and OrigSendingTime(122) not specified

Note: Always set OrigSendingTime to the time when the message was originally sent-not the present SendingTime and set PossDupFlag = "Y" when responding to a Resend Request
  1. Send Reject<3> (session-level) message referencing missing OrigSendingTime(122) (≥ FIX 4.2: SessionRejectReason(373) = 1 - "Required tag missing")
  2. Increment inbound MsgSeqNum
h. BeginString(8) value received as expected and specified in testing profile and matches BeginString on outbound messages Accept BeginString for the message
i. BeginString(8) value (e.g. "FIX.4.2") received did not match value expected and specified in testing profile or does not match BeginString on outbound messages
  1. Send Logout<5> message referencing incorrect BeginString value
  2. (optional) Wait for Logout<5> message response (note likely will have incorrect BeginString) or wait 2 seconds whichever comes first
  3. Disconnect
  4. Generate an "error" condition in test output
j. SenderCompID(49) and TargetCompID(56) values received as expected and specified in testing profile Accept SenderCompID and TargetCompID for the message
k. SenderCompID(49) and TargetCompID(56) values received did not match values expected and specified in testing profile
  1. Send Reject<3> (session-level) message referencing invalid SenderCompID or TargetCompID (≥ FIX 4.2: SessionRejectReason(373) = 9 - "CompID problem")
  2. Increment inbound MsgSeqNum(34)
  3. Send Logout<5> message referencing incorrect SenderCompID or TargetCompID value
  4. (optional) Wait for Logout<5> message response (note likely will have incorrect SenderCompID or TargetCompID) or wait 2 seconds whichever comes first
  5. Disconnect
  6. Generate an "error" condition in test output
l. BodyLength(9) value received is correct Accept BodyLength for the message
m. BodyLength(9) value received is not correct.
  1. Consider garbled and ignore message (do not increment inbound MsgSeqNum(34)) and continue accepting messages
  2. Generate a "warning" condition in test output
n. SendingTime(52) value received is specified in UTC (Universal Time Coordinated also known as GMT) and is within a reasonable time (e.g. 2 minutes) of atomic clock-based time Accept SendingTime for the message

o. SendingTime(52 value received is either not specified in UTC (Universal Time Coordinated also known as GMT) or is not within a reasonable time (e.g. 2 minutes) of atomic clock-based time.

Rationale: Verify system clocks on both sides are in sync and that SendingTime must be current time
  1. Send Reject<3> (session-level) message referencing inaccurate SendingTime (≥ FIX 4.2: SessionRejectReason(373) = 10 - "SendingTime accuracy problem")
  2. Increment inbound MsgSeqNum(34)
  3. Send Logout<5> message referencing inaccurate SendingTime value
  4. (optional) Wait for Logout<5> message response (note likely will have inaccurate SendingTime) or wait 2 seconds whichever comes first
  5. Disconnect
  6. Generate an "error" condition in test output.
p. MsgType(35 value received is valid (defined in spec or classified as user-defined) Accept MsgType for the message
q. MsgType(35) value received is not valid (defined in spec or classified as user-defined)
  1. Send Reject<3> (session-level) message referencing invalid MsgType (≥ FIX 4.2: SessionRejectReason(373) = 11 - "Invalid MsgType")
  2. Increment inbound MsgSeqNum(34)
  3. Generate a "warning" condition in test output
r. MsgType(35) value received is valid (defined in spec or classified as user-defined) but not supported or registered in testing profile
  1. If < FIX 4.2
    1. Send Reject<3> (session-level) message referencing valid but unsupported MsgType
  2. If ≥ FIX 4.2
    1. Send Business Message Reject<j> message referencing valid but unsupported MsgType (≥ FIX 4.2: BusinessRejectReason(380) = 3 - "Unsupported Message Type")
  3. Increment inbound MsgSeqNum(34)
  4. Generate a "warning" condition in test output
s. BeginString(8), BodyLength(9), and MsgType(35) are first three fields of message Accept the message
t. BeginString(8), BodyLength(9), and MsgType(35) are not the first three fields of message
  1. Consider garbled and ignore message (do not increment inbound MsgSeqNum(34)) and continue accepting messages
  2. Generate a "warning" condition in test output
3   Receive Message Standard Trailer Mandatory a. Valid CheckSum(10) Accept Message
b. Invalid CheckSum(10)
  1. Consider garbled and ignore message (do not increment inbound MsgSeqNum(34)) and continue accepting messages
  2. Generate a "warning" condition in test output
c. Garbled message
  1. Consider garbled and ignore message (do not increment inbound MsgSeqNum(34)) and continue accepting messages
  2. Generate a "warning" condition in test output
d. CheckSum(10) is last field of message, value has length of 3, and is delimited by <SOH> Accept Message
e. CheckSum(10) is not the last field of message, value does not have length of 3, or is not delimited by <SOH>
  1. Consider garbled and ignore message (do not increment inbound MsgSeqNum(34)) and continue accepting messages
  2. Generate a "warning" condition in test output.
4   Send Heartbeat<0> message Mandatory a. No data sent during preset heartbeat interval (HeartBeatInt(108) field) Send Heartbeat message
b. A Test Request<1> message is received Send Heartbeat<0> message with Test Request message's TestReqID(112)
5   Receive Heartbeat<0> message Mandatory Valid Heartbeat<0> message Accept Heartbeat<0> message
6   Send Test Request<1> Mandatory No data received during preset heartbeat interval (HeartBeatInt(108) field) + "some reasonable period of time" (use 20% of HeartBeatInt field)
  1. Send Test Request message
  2. Track and verify that a Heartbeat<0> with the same TestReqID(112) is received (may not be the next message received)
7   Receive Reject<3> message Mandatory Valid Reject message
  1. Increment inbound MsgSeqNum(34)
  2. Continue accepting messages
8   Receive Resend Request<2> message Mandatory Valid Resend Request Respond with application level messages and SequenceReset-Gap Fill<4> for admin messages in requested range according to "Message Recovery" rules
9   Synchronize sequence numbers Optional Application failure Send Sequence Reset - Reset<4> message or manually reset to 1 out-of-band
10   Receive Sequence Reset (Gap Fill)<4> Mandatory a. Receive Sequence Reset (Gap Fill) message with NewSeqNo(36) > MsgSeqNum(34) and MsgSeqNum > than expect sequence number Issue Resend Request<2> to fill gap between last expected MsgSeqNum & received MsgSeqNum
b. Receive Sequence Reset (Gap Fill)<4> message with NewSeqNo(36) > MsgSeqNum(34) and MsgSeqNum = to expected sequence number Set next expected sequence number = NewSeqNo
c. Receive Sequence Reset (Gap Fill)<4> message with NewSeqNo(36) > MsgSeqNum(34) and MsgSeqNum < than expected sequence number and PossDupFlag(43) = "Y" Ignore message
d. Receive Sequence Reset (Gap Fill)<4> message with NewSeqNo(36) > MsgSeqNum(34) and MsgSeqNum < than expected sequence number and without PossDupFlag(43) = "Y"
  1. If possible send a Logout<5> message with text of "MsgSeqNum too low, expecting X received Y", prior to disconnecting FIX session
  2. (optional) Wait for Logout message response (note likely will have inaccurate MsgSeqNum) or wait 2 seconds whichever comes first
  3. Disconnect
  4. Generate an "error" condition in test output
e. Receive Sequence Reset (Gap Fill)<4> message with NewSeqNo(36) ≤ MsgSeqNum(34) and MsgSeqNum = to expected sequence number Send Reject<3> (session-level) message with message "attempt to lower sequnce number, invalid value NewSeqNum=<x>"
11   Receive Sequence Reset (Reset)<4> Mandatory a. Receive Sequence Reset (reset) message with NewSeqNo(36) > than expected sequence number
  1. Accept the Sequence Reset (Reset) message without regards to its MsgSeqNum(34)
  2. Set expected sequence number equal to NewSeqNo
b. Receive Sequence Reset (Reset)<4> message with NewSeqNo(36) = to expected sequence number
  1. Accept the Sequence Reset (Reset) message without regards to its MsgSeqNum(34)
  2. Generate a "warning" condition in test output
c. Receive Sequence Reset (Reset)<4> message with NewSeqNo(36) < than expected sequence number
  1. Accept the Sequence Reset (Reset) message without regards to its MsgSeqNum(34)
  2. Send Reject<3> (session-level) message referencing invalid MsgType(35) (≥ FIX 4.2: SessionRejectReason(373) = 5 - "Value is incorrect (out of range) for this tag")
  3. Do NOT Increment inbound MsgSeqNum
  4. Generate an "error" condition in test output
  5. Do NOT lower expected sequence number
12   Initiate logout process Mandatory Initiate Logout
  1. Send Logout<5> message
  2. Wait for counterparty to respond with Logout message up to 10 seconds (note may not be received if communications problem exists). If not received, generate a “warning” condition in test output.
  3. Disconnect
13   Receive Logout message Mandatory a. Receive valid Logout<5> message in response to a solicited logout process Disconnect without sending a message
b. Receive valid Logout<5> message unsolicitied
  1. Send Logout response message
  2. Wait for counterparty to disconnect up to 10 seconds. If max exceeded, disconnect and generate an “error” condition in test output.
14   Receive application or administrative message Mandatory a. Receive field identifier (tag number) not defined in specification.
Exception: undefined tag used is specified in testing profile as user-defined.
  1. Send Reject<3> (session-level) message referencing invalid tag number (≥ FIX 4.2: SessionRejectReason(373) = 0 - "Invalid tag number")
  2. Increment inbound MsgSeqNum(34)
  3. Generate an "error" condition in test output
b. Receive message with a required field identifier (tag number) missing.
  1. Send Reject (session-level) message referencing required tag missing (≥ FIX 4.2: SessionRejectReason(373) = 1 - "Required tag missing")
  2. Increment inbound MsgSeqNum(34)
  3. Generate an "error" condition in test output
c. Receive message with field identifier (tag number) which is defined in the specification but not defined for this message type.
Exception: undefined tag used is specified in testing profile as user-defined for this message type.
  1. Send Reject<3> (session-level) message referencing tag not defined for this message type (≥ FIX 4.2: SessionRejectReason(373) = 2 - "Tag not defined for this message type")
  2. Increment inbound MsgSeqNum(34)
  3. Generate an "error" condition in test output
d. Receive message with field identifier (tag number) specified but no value (e.g. "55=<SOH>" vs. "55=IBM<SOH>").
  1. Send Reject<3> (session-level) message referencing tag not defined for this message type (≥ FIX 4.2: SessionRejectReason(373) = 4 - "Tag specified without a value")
  2. Increment inbound MsgSeqNum(34)
  3. Generate an "error" condition in test output
e. Receive message with incorrect value (out of range or not part of valid list of enumerated values) for a particular field identifier (tag number).
Exception: undefined enumeration values used are specified in testing profile as user-defined.
  1. Send Reject<3> (session-level) message referencing tag not defined for this message type (≥ FIX 4.2: SessionRejectReason(373) = 5 - "Value is incorrect (out of range) for this tag")
  2. Increment inbound MsgSeqNum(34)
  3. Generate an "error" condition in test output
f. Receive message with a value in an incorrect data format (syntax) for a particular field identifier (tag number).
  1. Send Reject<3> (session-level) message referencing tag not defined for this message type (≥ FIX 4.2: SessionRejectReason(373) = 6 - "Incorrect data format for value")
  2. Increment inbound MsgSeqNum(34)
  3. Generate an "error" condition in test output
g. Receive a message in which the following is not true: Standard Header fields appear before Body fields which appear before Standard Trailer fields.
  1. Send Reject<3> (session-level) message referencing incorrect message structure header+body+trailer (≥ FIX 4.3: SessionRejectReason(373) = 14 - "Tag specified out of required order")
  2. Increment inbound MsgSeqNum(34)/li>
  3. Generate an "error" condition in test output
h. Receive a message in which a field identifier (tag number) which is not part of a repeating group is specified more than once
  1. Send Reject<3> (session-level) message referencing duplicate field identifier (tag number) (≥ FIX 4.3: SessionRejectReason(373) = 13 "Tag appears more than once")
  2. Increment inbound MsgSeqNum(34)
  3. Generate an "error" condition in test output
i. Receive a message with repeating groups in which the "count" field value for a repeating group is incorrect
  1. Send Reject<3> (session-level) message referencing the incorrect "count" field identifier (tag number) (≥ FIX 4.3: SessionRejectReason(373) = 16 - "Incorrect NumInGroup count for repeating group")
  2. Increment inbound MsgSeqNum(34)
  3. Generate an "error" condition in test output
j. Receive a message with repeating groups in which the order of repeating group fields does not match the specification.
  1. Send Reject<3> (session-level) message referencing the repeating group with incorrect field ordering (≥ FIX 4.3: SessionRejectReason(373) = 15 "Repeating group fields out of order")
  2. Increment inbound MsgSeqNum(34)
  3. Generate an "error" condition in test output
k. Receive a message with a field of a data type other than "data" which contains one or more embedded <SOH> values.
  1. Send Reject<3> (session-level) message referencing field identifier (tag number) with embedded <SOH> (≥ FIX 4.3: SessionRejectReason(373) = 17 - "Non "data" value includes field delimiter (SOH character)")
  2. Increment inbound MsgSeqNum(34)
  3. Generate an "error" condition in test output

  4. Discard as valid response/outcome too
    or
    Consider garbled and ignore message
l. Receive a message when application-level processing or system is not available (Optional)
  1. If < FIX 4.2
    1. Send Reject<3> (session-level) message referencing application message processing is not available
  2. If ≥ FIX 4.2
    1. Send Business Message Reject<j> message referencing application message processing is not available (≥ FIX 4.2: BusinessRejectReason(380) = 4 - "Application not available")
  3. Increment inbound MsgSeqNum(34)
  4. Generate a "warning" condition in test output
m. Receive a message in which a conditionally required field is missing
  1. If < FIX 4.2
    1. Send Reject<3> (session-level) message referencing field identifier (tag number) of the missing conditionally required field(s)
  2. If ≥ FIX 4.2
    1. Send Business Message Reject<j> message referencing field identifier (tag number) of the missing conditionally required field(s) (≥ FIX 4.2: BusinessRejectReason(380) = 5 - "Conditionally Required Field Missing")
  3. Increment inbound MsgSeqNum(34)
  4. Generate an "error" condition in test output
n. Receive a message in which a field identifier (tag number) appears in both cleartext and encrypted section but has different values
  1. Send Reject<3> (session-level) message referencing field identifier (tag number) missing from unencrypted section (≥ FIX 4.2: SessionRejectReason(373) = 7 - "Decryption problem")
  2. Increment inbound MsgSeqNum(34)
  3. Generate an "error" condition in test output
15   Send application or administrative messages to test normal and abnormal behavior/response   Send more than one message of the same type with header and body fields ordered differently to verify acceptance. (Exclude those which have restrictions regarding order) Messages accepted and subsequent messages’ MsgSeqNum(34) are accepted
16   Queue outgoing messages Mandatory a. Message to send/queue while disconnected

Queue outgoing messages. Note there are two valid approaches:

  1. Queue without regards to MsgSeqNum(34)
    1. Store data for messages
  2. Queue each message with the next MsgSeqNum value
    1. Store data for messages in such a manner as to use and "consume" the next MsgSeqNum(34)

Note: SendingTime(52): must contain the time the message is sent not the time the message was queued
b. Re-connect with queued messages

  1. Complete logon process (connect, and Logon<A> message exchange)
  2. Complete MsgSeqNum recovery process if applicable
  3. Recommended short delay or TestRequest<1>/Heartbeat<0> to verify MsgSeqNum recovery completed
  4. Note there are two valid queuing approaches:
    1. Queue without regards to MsgSeqNum(34)
      1. Send queued messages with new MsgSeqNum values (greater than Logon message’s MsgSeqNum)
    2. Queue each message with the next MsgSeqNum value
      1. (note Logon<A> message’s MsgSeqNum will be greater than the queued messages' MsgSeqNum)
      2. Counterparty will issue ResendRequest<2> requesting the range of missed messages
      3. Resend each queued message with PossDupFlag(43) set to "Y"

Note: SendingTime(52): must contain the time the message is sent not the time the message was queued
17   Support encryption Optional a. Receive Logon<A> message with valid, supported EncryptMethod(98)
  1. Accept the message
  2. Perform the appropriate decryption and encryption method readiness
  3. Respond with Logon message with the same EncryptMethod
b. Receive Logon<A> message with invalid or unsupported EncryptMethod(98)
  1. Send Reject<3> (session-level) message referencing invalid or unsupported EncryptMethod value (≥ FIX 4.2: SessionRejectReason(373) = 7 - "Decryption problem")
  2. Increment inbound MsgSeqNum(34)
  3. Send Logout<5> message referencing invalid or unsupported EncryptMethod value
  4. (optional) Wait for Logout message response (note could have decrypt problems) or wait 2 seconds whichever comes first
  5. Disconnect
  6. Generate an "error" condition in test output
c. Receive message with valid SignatureLength(93) and Signature(89) values Accept the message
d. Receive message with invalid SignatureLength(93) value
  1. Send Reject<3> (session-level) message referencing invalid SignatureLength value (≥ FIX 4.2: SessionRejectReason(373) = 8 - "Signature problem")
  2. Increment inbound MsgSeqNum(34)
  3. Generate an "error" condition in test output
e. Receive message with invalid Signature(89) value

Process message:

  1. Send Reject<3> (session-level) message referencing invalid Signature value (≥ FIX 4.2: SessionRejectReason(373) = 8 - "Signature problem")
  2. Increment inbound MsgSeqNum(34)
  3. Generate an "error" condition in test output

Or consider decryption error or message out of order, ignore message (do not increment inbound MsgSeqNum) and continue accepting messages
f. Receive message with a valid SecureDataLen(90) value and a SecureData(91) value that can be decrypted into valid, parse-able cleartext Accept the message
g. Receive message with invalid SecureDataLen(90) value
  1. Consider decryption error or message out of order, ignore message (do not increment inbound MsgSeqNum) and continue accepting messages
  2. Generate a "warning" condition in test output
h. Receive message with a SecureData(91) value that cannot be decrypted into valid, parse-able cleartext
  1. Send Reject<3> (session-level) message referencing invalid SecureData value (≥ FIX 4.2: SessionRejectReason(373) = 7 - " Decryption problem")
  2. Increment inbound MsgSeqNum(34)
  3. Generate a "warning" condition in test output
i. Receive message with one or more fields not present in the unencrypted portion of the message that "must be unencrypted" according to the spec
  1. Send Reject<3> (session-level) message referencing field identifier (tag number) missing from unencrypted section (≥ FIX 4.2: SessionRejectReason(373) = 7 - " Decryption problem")
  2. Increment inbound MsgSeqNum(34)
  3. Generate a "warning" condition in test output
j. Receive message with incorrect handling of "left over" characters (e.g. when length of clear text prior to encryption is not a multiple of 8) according to the specified EncryptMethod(98)
  1. Send Reject<3> (session-level) message referencing incorrect handling of "left over" characters during encryption (≥ FIX 4.2: SessionRejectReason(373) = 7 - " Decryption problem")
  2. Increment inbound MsgSeqNum(34)
  3. Generate a "warning" condition in test output
18   Support third party addressing Optional a. Receive messages with OnBehalfOfCompID(115) and DeliverToCompID(128) values expected as specified in testing profile and with correct usage Accept messages
b. Receive messages with OnBehalfOfCompID(115) or DeliverToCompID(128) values not specified in testing profile or incorrect usage
  1. SendReject<3> (session-level) message referencing invalid OnBehalfOfCompID or DeliverToCompID (≥ FIX 4.2: SessionRejectReason(373) = 9 - "CompID problem")
  2. Increment inbound MsgSeqNum(34)
  3. Generate a "warning" condition in test output
19   Test PossResend handling Mandatory a. Receive message with PossResend(97) = "Y" and application-level check of Message specific ID indicates that it has already been seen on this session
  1. Ignore the message
  2. Generate a "warning" condition in test output
b. Receive message with PossResend(97) = "Y" and application-level check of Message specific ID indicates that it has NOT yet been seen on this session Accept and process the message normally
20   Simultaneous Resend request test Mandatory Receive a Resend Request<2> message while having sent and awaiting complete set of responses to a Resend Request message
  1. Perform resend of requested messages
  2. Send Resend Request to request missed messages

OnixS
OnixS

Search the site