Acknowledgements | HL7 MLLP Connector for Azure Logic Apps

Acknowledgement mode

Mode	BizTalk equivalent	Behaviour
Auto (default)	One-way MLLP receive location, HL7 pipeline generating ACKs	The ACK is sent once the run is accepted (persisted, for stateful workflows). AE/CE if the run can't be started.
Workflow	Two-way (request-response) receive location	The sender waits until the workflow calls Send acknowledgement (gateway: the workflow's Response body). After responseTimeoutSeconds, timeoutBehavior applies: SendNegativeAck, CloseConnection or NoResponse.
None	One-way, no ACK	Nothing is returned.

Acknowledgement type

Type	Behaviour
Original (default)	MSH-15 and MSH-16 empty: AA / AE / AR. If the sender filled them in (enhanced mode): commit ACK CA / CE / CR according to MSH-15 (AL, NE, ER, SU).
Enhanced	CA / CE / CR according to MSH-15; an empty MSH-15 means AL.
StaticOriginal	Always AA / AE / AR.
StaticEnhanced	Always CA / CE / CR.
None	Never.

Trigger inputs

Input	Values	Default
`acknowledgementMode`	Auto \| Workflow \| None	Auto
`acknowledgementType`	Original \| Enhanced \| StaticOriginal \| StaticEnhanced \| None	Original
`responseTimeoutSeconds`	Workflow mode: how long the sender waits for Send acknowledgement	60
`timeoutBehavior`	SendNegativeAck \| CloseConnection \| NoResponse	SendNegativeAck
`batchMode`	Split \| Single \| Reject	Split
`rejectInvalidMessages`	Answer AR/CR, without a run, when MSH-9, -10, -11 or -12 is missing	true
`maxConnections, maxMessageSizeKB, idleTimeoutSeconds`	Connection limits	100, 16384, 600
`archive`	Archive each received frame and its ACK	false

What generated ACKs contain

Header: sender and receiver swapped; MSH-11, MSH-12 and MSH-18 copied; ACK^<event>^ACK for v2.3.1 and later.
MSA-2 echoes the message's MSH-10. Negative ACKs add an ERR segment.
Internal error details are logged, never sent to the sender.
Enhanced mode: the connector sends the commit ACK. When the sender also asks for an application ACK (trigger output applicationAckRequested), build it with Create acknowledgement and send it with Send message.

Workflow ACKs through the gateway

Return the ACK from a Response action, as plain HL7 or as JSON. Here the codec's Decode has already built it:

"Return_ACK": {
  "type": "Response",
  "kind": "Http",
  "inputs": {
    "statusCode": 200,
    "body": { "acknowledgement": "@{body('Decode_HL7')?['ack']}" }
  }
}