MLLP Adapter Known Issues
This section contains useful information that may help you avoid Minimal Lower Layer Protocol (MLLP) adapter errors.
Two-way MLLP adapter might not detect a problem with an ACK
When Microsoft BizTalk Accelerator for HL7 (BizTalk Accelerator for HL7 (BTAHL7)) receives an acknowledgment (ACK) on a two-way MLLP adapter, the adapter performs a lightweight validation on the ACK to determine its validity. If it is found to be valid, the MSA1 field is extracted, and depending on its value, the adapter retries, suspends, or deletes the original message to which the ACK was responding. However, since the validation performed by the adapter is not a complete validation, it is possible that the adapter will not detect a problem with the ACK. For instance, the adapter could determine that the ACK is valid, and delete the original message, whereas the pipeline would determine that the ACK was not well-formed, and suspend the ACK message.
MLLP performance counters do not count ACKs
One measure of performance is the number of messages processed by an MLLP adapter, as indicated by MLLP performance counters. This count measures the number of messages received or transmitted. However, the count does not measure the number of ACKs either received or sent.
MLLP adapter connection names are not guaranteed to be unique
BTAHL7 does not guarantee the uniqueness of the connection name entered in the property pages of an MLLP adapter. Ensure that descriptive and relevant connection names are entered in this required field. Using connection names that represent line-of-business applications can be useful when trying to understand the behavior of the connection. For example, PerfMon counters use the connection name.
Note
BTAHL7 does ensure the uniqueness of receive locations or send port names.
Two-way MLLP adapters do not send Commit ACKs for all messages in a batch
When you configure each message in a batch to generate a Commit ACK, and the system sends the batch to a two-way MLLP receive adapter, the adapter will only send the Commit ACK corresponding to the first message in the batch.
Note
It is recommended that you use a one-way MLLP adapter to transport batches.
NAK generated by two-way MLLP adapter
When a two-way MLLP adapter suspends any message, the MLLP adapter generates a NAK (negative acknowledgment) and places it in the MessageBox database. This may be unexpected behavior. You may want to remove the NAK from the MessageBox database or map it into another message.
Two-way MLLP adapter only supports the 2.X message format
The two-way MLLP adapter currently supports only the 2.X message format.
Two-way MLLP adapter does not support static acknowledgments
The two-way send adapter does not support processing static acknowledgments.