Interface: NackEvent

Payload of the server 'nack' event, emitted whenever the server responds with a negative acknowledgement instead of AA on the auto-ACK path (the fail-safe commit contract). This fires both when a commit-gated autoAck: 'AA' handler throws/rejects and when the server downgrades a positive auto-ACK because the inbound could not be correlated (NackReason).

PHI-safe by construction: carries only the connection ID, the resolved acknowledgement code, and a static reason, never the payload, the inbound control ID, or the thrown error's message (which may carry PHI). The object is Object.freeze()'d before emission.

Example

server.on('nack', ({ connectionId, ackCode, reason }) => {
  metrics.increment('mllp.nack', { code: ackCode, reason }); // e.g. reason='discarded-bytes'
});

Properties

ackCode

readonly ackCode: NegativeAckCode

The negative acknowledgement code sent to the peer (AE or AR).

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connectionId

readonly connectionId: string

Connection that produced the negative acknowledgement.

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reason

readonly reason: NackReason

Why the negative acknowledgement was sent (PHI-free).