Enum DeadLetterReason 

#[non_exhaustive]
pub enum DeadLetterReason {
    UnknownPid(u32),
    UnknownConversation {
        conversation_id: String,
    },
    VersionMismatch {
        expected: String,
        received: String,
    },
    DuplicateMessage {
        inbox_key: String,
    },
    ProcessingError {
        message: String,
    },
    OutboxExhausted {
        message_id: OutboxMessageId,
        message_type: String,
        recipient: String,
        last_error: String,
        attempts: u32,
    },
}

Structured reason why an inbound message was rejected.

The variant gives the dispatch path enough information to emit an actionable CONTRL or log entry. Adding new variants is a non-breaking change thanks to #[non_exhaustive].

Variants (Non-exhaustive)

Non-exhaustive enums could have additional variants added in future. Therefore, when matching against variants of non-exhaustive enums, an extra wildcard arm must be added to account for any future variants.

UnknownPid(u32)

No workflow is registered for this PID in the PidRouter.

The PID is either from a future BDEW release not yet deployed or a malformed message. Respond with a CONTRL negative acknowledgement.

UnknownConversation

No in-flight process matched the inbound conversation_id.

This typically means the process completed, was never started, or the ProcessRegistry was lost on restart (see.

Fields

conversation_id: String

The conversation_id from the inbound EDIFACT interchange.

VersionMismatch

The message’s format version has no registered MessageAdapter.

Either the adapter registry is incomplete (see or the sender is using a deprecated / future format version.

Fields

expected: String

The format version string the adapter registry expected.

received: String

The format version string carried in the inbound message.

DuplicateMessage

A message with this inbox key was already accepted (AS4 duplicate).

The AS4 sender retries for up to 72 hours. The InboxStore detected the duplicate and the message must not be processed again.

Fields

inbox_key: String

The inbox deduplication key (typically the AS4 MessageId).

ProcessingError

A workflow or adapter returned a processing error.

The message was routed correctly but could not be processed. Use this variant when the failure is definitive (not retriable).

Fields

message: String

Short, human-readable description of the failure.

OutboxExhausted

The outbox delivery worker gave up after exhausting all retry attempts.

The message was re-queued max_attempts times and never successfully delivered to the AS4 endpoint (or ERP webhook). The message is removed from the outbox and recorded here for regulatory audit.

Fields

message_id: OutboxMessageId

The outbox message ID of the undeliverable message.

message_type: String

The message type (e.g. "APERAK", "CONTRL").

recipient: String

The intended recipient GLN.

last_error: String

The last error returned by the AS4 sender.

attempts: u32

How many delivery attempts were made.

Implementations

impl DeadLetterReason

pub fn label(&self) -> &'static str

Short label identifying the rejection category.

Suitable for structured log fields and metric labels.

Trait Implementations

impl Clone for DeadLetterReason

fn clone(&self) -> DeadLetterReason

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for DeadLetterReason

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Display for DeadLetterReason

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.