Struct MqttMessage 

pub struct MqttMessage { /* private fields */ }

A message delivered by an MqttSubscriber.

ack acknowledges through the protocol for QoS 1 (PUBACK) and QoS 2 (PUBREC, with the client completing the handshake); QoS 0 deliveries report AckError::Unsupported. MQTT has no negative acknowledgement, so nack(requeue = true) reports AckError::Unsupported as well - unacknowledged messages redeliver when the session resumes - and nack(requeue = false) acknowledges (dropping is the only terminal outcome the protocol offers).

A handler’s HandlerOutcome::retry() settles through that refused negative acknowledgement, so it does not retry inside the live connection: the delivery stays unacknowledged and comes back only when a persistent session resumes. retry_after with a retry publisher is the outcome that retries within the session. The site’s retry and retry_after pages show both in a service.

A delivery reports no redelivery count. The protocol carries a duplicate flag and no counter, so a registration’s cap is counted on the framework’s retry-count header instead, which the copies the runtime publishes carry.

Implementations

impl MqttMessage

pub fn topic(&self) -> &str

The topic this message was published to (the real topic, never a $share filter).

pub const fn qos(&self) -> Qos

The quality of service this message was delivered at: the lesser of the one it was published with and the one its subscription asked for.

A delivery at Qos::AtMostOnce carries no acknowledgement, so ack reports AckError::Unsupported for it.

Trait Implementations

impl BuildContext<MqttMessage> for MqttContext

fn build(msg: &MqttMessage) -> Self

Builds the context value by reading fields out of msg.

impl Debug for MqttMessage

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

Formats the value using the given formatter.

impl IncomingMessage for MqttMessage

fn partition_key(&self) -> Option<&[u8]>

The PARTITION_KEY_HEADER value the publisher set, which keyed worker lanes (workers(n, by_key)) order by.

fn payload(&self) -> &[u8]

Returns the raw payload of the message.

fn headers(&self) -> &HeaderMap

Returns the headers attached to the message.

async fn ack(self) -> Result<(), AckError>

Acknowledges successful processing. Consumes the message handle.

async fn nack(self, requeue: bool) -> Result<(), AckError>

Negatively acknowledges the message. When requeue is true the broker should redeliver according to its own retry policy; when false it should drop or dead-letter the message.

fn redelivery_count(&self) -> Option<u64>

How many times the broker has delivered this message, counting this delivery. None where the transport counts nothing.

fn decode_error(&self) -> Option<&CodecError>

The error the broker met while reading this delivery, or None when it read the delivery whole.

fn supports_nack_after(&self) -> bool

Reports whether this transport can honor nack_after natively.

fn nack_after( self, delay: Duration, ) -> impl Future<Output = Result<(), AckError>> + Send

where Self: Sized,

Negatively acknowledges the message, asking the broker to redeliver it no sooner than delay from now.

impl Partitioned for MqttMessage

The key a delivery is ordered by. MQTT has no partitions, so the key is the PARTITION_KEY_HEADER the publisher set.

fn partition_key(&self) -> Option<&[u8]>

Returns the partition key for this item, or None if the broker should pick a partition.