Destination Nodes

A destination node delivers a message out of the workflow. It consumes from the node connected before it and performs the external side effect.

Fields marked needed to start must have a usable value before the node will start.

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Destination LLP

Sends HL7 v2 over MLLP to a remote host and handles the ACK.

Core fields

Field	Default	Notes
Remote Host	localhost	Needed to start. Hostname or IP of the receiving system.
Remote Port	5145	Needed to start, and must be greater than 0.
Message Encoding	Western (ISO-8859-1)	Character encoding for outbound messages.
Escape 8-Bit Characters	off	Escape high-bit characters in the outbound stream.
Persistent Connection	Yes	Yes reuses one connection; No connects per message.

:::caution Check Remote Host before you start The default is localhost, which is a valid value — so a node you forgot to configure starts cleanly and sends nowhere useful. Set it deliberately, and check it after importing a project from another environment. :::

Framing

Field	Default
LLP Delimiters	Normal LLP
Messages Begin After	\x0B
Messages Continue Until	\x1C\x0D

Acknowledgment

Field	Default	Notes
Wait for Ack	on	Whether to wait for an ACK before treating the message as delivered.
Ack Timeout	10000	Milliseconds to wait for the ACK.
Ack Verification	Any message	Any message, or Original ID and message type for a strict match.
Ack Error Handling	Stop channel	Stop channel, Queue message, or Discard message.

Resend and reconnect

Field	Default	Notes
Resend on Ack Timeout	on	Resend when no ACK arrives in time.
Resend on Ack Verification Failure	off	Resend when the ACK does not match.
Resend Attempts Unlimited	off
Resend Attempts	5
Disconnect Between Resend Attempts	on
Reconnect After Resend	10000	Milliseconds.
Attempt to Reconnect	Yes, with limit	No, Yes, or Yes, with limit.
Reconnect Attempts	60	With Yes, with limit.
Reconnection Interval	10000	Milliseconds between attempts.

TLS

Field	Default	Notes
Use SSL	on	This node defaults to TLS.
Certificate File	(empty)
Private Key File	(empty)
Verify Peer	on
Certificate Authority File	(empty)

:::note This node defaults to TLS on, and Source LLP defaults to off If you are connecting two Linkiir installations, or sending to a receiver that expects plain MLLP, the defaults will not match. A TLS mismatch usually looks like a connection that opens and immediately drops. Set Use SSL on both ends deliberately rather than relying on defaults. :::

Choosing Ack Error Handling

This is the most consequential setting on the node. It decides what happens when the receiver returns a negative ACK.

Setting	Behaviour	Use when
Stop channel	The node stops	Safest default. A rejection needs a human decision, and stopping preserves order and prevents a flood of failures.
Queue message	The message is held and the node continues	Rejections are expected for individual messages and must be retained for review.
Discard message	The message is dropped and the node continues	Rarely appropriate for clinical or financial data. Choose it only when loss is genuinely acceptable.

Start with Stop channel. It surfaces a receiver problem immediately instead of letting hundreds of messages fail unnoticed. Stopping is safe: unprocessed messages wait in the durable queue.

Wait for Ack and Ack Verification

Combination	Meaning
Wait for Ack off	Delivered once written to the socket. Fastest, weakest guarantee.
On, Any message	Any response counts as an acknowledgment.
On, Original ID and message type	The ACK must match the message sent. Strongest guarantee.

Use Original ID and message type when the receiver may respond out of order or on a shared connection. Without it, an ACK for one message can be credited to another — which means a message that was actually rejected is recorded as delivered.

Persistent Connection

Set Yes when the receiver expects a long-lived connection and the volume justifies it. Set No when the receiver is intolerant of idle connections, or when a network device between you closes them silently — a closed-but-not-noticed connection produces confusing timeouts.

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Destination File/FTP

Writes each message to a file, locally or to an FTP/FTPS/SFTP server.

Core fields

Field	Default	Notes
Output Directory	(empty)	Needed to start. Where files are written.
Write Each Message To	Separate files	Separate files or A single file.
Single File	(empty)	The target filename, with A single file.
Output File Encoding	Western (ISO-8859-1)	Character encoding of written files.
Escape 8-Bit Characters	off	Escape high-bit characters on output.

Naming files, with Separate files

Field	Default	Notes
Use as File ID	Unique ID (YYYYMMDDhhmmss_XXXXX)	See the table below.
Custom Timestamp Format	output_%Y_%m_%d_%H_%M_%S_%f.hl7	With Custom Timestamp.
Number of Padded Digits	5	3 to 7, with Padded integer index.
Next File Index	0	Starting number, with either index mode.
Output File Mask	%i.txt	Needed to start with Separate files. Filename pattern.
Temporary File Extension	tmp	Extension used while writing.

Choosing a file ID

Option	Suits
Unique ID (YYYYMMDDhhmmss_XXXXX)	Default choice. Safe under any volume and after a restart.
Timestamp (to the millisecond)	Human-scannable output, if two messages cannot share a millisecond.
Custom Timestamp	A receiver that parses filenames.
Integer index	A receiver that expects a sequence.
Padded integer index	A receiver that sorts filenames as text.

Timestamp naming collides under load when two messages land in the same interval, and index naming restarts from Next File Index if that value is ever reset. Use Unique ID unless a receiver requires otherwise.

The temporary extension matters

Linkiir writes to a temporary name and renames on completion, so a downstream watcher configured to pick up *.txt never sees a partial file.

Keep Temporary File Extension different from the extension in Output File Mask. If they match, a reader can grab a file mid-write — which is exactly the failure the temporary name exists to prevent.

FTP upload

Turn on Upload to FTP to write to a remote server.

Field	Default	Notes
FTP Protocol	FTP	FTP, FTPS (FTP over SSL), or SFTP (Secure Shell FTP).
Authentication	Username/Password	Username/Password or Private/Public Key.
FTP Server	(empty)	Needed to start when Upload to FTP is on.
FTP Port	21
FTP Username	(empty)	Needed to start when Upload to FTP is on.
FTP Password	(empty)	For password authentication.
FTP Path	(empty)	Remote directory.
Certificate File, Private Key File	(empty)	For FTPS.
SFTP Private Key File, Public Key File	(empty)	For key-based SFTP.
Verify Peer	off	Leave on outside a trusted network.
Verify Host Fingerprint	off	Leave on outside a trusted network.
Use Remote Temporary File	on	Upload under a temporary name and rename on completion.
FTP Overwrite Handling	be overwritten	An existing file may be overwritten, be renamed, or not be uploaded.
Keep Local Files	on	Retain a local copy after upload.
Attempt to Reconnect	No	No, Yes (unlimited), or Yes, with limit.
Reconnect Limit Times	60	With Yes, with limit.
Reconnection Interval	10000	Milliseconds between attempts.

Leave Use Remote Temporary File on whenever the receiver polls the upload directory, for the same reason as the local temporary extension.

Keep Local Files is on by default, which is useful while validating a new interface — the local copies are your evidence of what was sent. Plan for the disk they consume, or turn it off once the interface is established.

:::caution FTP Overwrite Handling defaults to overwriting The default silently replaces an existing remote file of the same name. Combined with timestamp or index naming, a redelivery can overwrite a file the receiver has not read yet. Set it to not be uploaded when silent replacement would lose data. :::

Put the password in the project's Credentials tab flagged Secret, and reference it. See Project Settings.

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Outbound HTTP, email, and database writes

There is no working dedicated node type for these. Make the call from a Transform Custom node:

local linkiir = require("linkiir")

function main(Data)
   local resp, err = linkiir.link.web.post{
      url = "https://api.example.com/messages",
      body = Data,
      headers = { ["Content-Type"] = "application/json" },
      auth = { type = "bearer", token = Token },
      timeout = 30,
   }
   if not resp then
      error("delivery failed: " .. err.message)
   end
   if resp.code >= 400 then
      error("receiver returned " .. resp.code)
   end
end

A transform node that calls out and never pushes is a destination in every practical sense.

Raising an error on a failed delivery matters: it stops the message being treated as delivered, so it is not silently lost. Check both the transport result and the status code — resp being present means the request completed, not that the receiver accepted it. See Error Handling and Retry.

:::note Destination Custom is not usable The palette offers Custom under Destination, but it has no runtime implementation in this release. Use Transform Custom as above. :::

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Make delivery idempotent

Delivery is at-least-once, so a message can be delivered twice after an interruption or a retry.

Destination	How to protect the receiver
Destination LLP	Use Original ID and message type verification and let the receiver deduplicate on message control ID.
Destination File/FTP	Use Unique ID naming and FTP Overwrite Handling set to not be uploaded, so a redelivery cannot silently replace a file.
Outbound HTTP	Send a stable idempotency key derived from the message, if the API supports one.
Database write	Use an upsert or guarded insert keyed on a message identifier.

Decide how the receiver detects duplicates before you go live, not after. A replay or retry must not create a duplicate clinical or financial transaction.

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Next

• Source Nodes
• Custom Scripting Nodes
• Error Handling and Retry