Struct Message 

pub struct Message {
    pub payload: Payload,
    pub headers: HashMap<String, String>,
}

A message containing a payload and headers (metadata).

Automatic Message ID

On construction a UUID v4 is inserted under the message_id header. While you can override this with set_header, it is discouraged—other infrastructure (logging, tracing) may rely on uniqueness.

Correlation ID

Not created automatically to avoid overhead if unused. Call Message::ensure_correlation_id when a processor needs it. Subsequent calls return the same stable value.

Header Semantics

All headers are simple UTF-8 strings. Keep values small; store large / complex structures in the payload or properties instead.

Fields

payload: Payload

The message payload.

headers: HashMap<String, String>

Arbitrary string headers for metadata.

Implementations

impl Message

pub fn new(payload: Payload) -> Message

Creates a new message with the given payload.

pub fn from_text<T>(s: T) -> Message

where T: Into<String>,

Creates a new text message.

pub fn body_text(&self) -> Option<&str>

Returns the message body as text, if available.

pub fn header(&self, key: &str) -> Option<&str>

Returns the value of a header, if present.

pub fn set_header<K, V>(&mut self, k: K, v: V)

where K: Into<String>, V: Into<String>,

Sets a header key-value pair.

pub fn ensure_correlation_id(&mut self) -> &str

Ensures a correlation id header exists; returns its value.

If a correlation_id header is present it is returned unchanged; otherwise a new UUID v4 is generated, inserted, and then returned.

Use Cases

• Aggregator / Splitter patterns grouping related messages.
• Request/Reply correlation.
• Distributed tracing boundary (can pair with trace/span ids).

Prefer calling once early (or using CorrelationInitializer) rather than sprinkling calls across processors.

Trait Implementations

impl Clone for Message

fn clone(&self) -> Message

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for Message

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

Formats the value using the given formatter.

impl Default for Message

fn default() -> Message

Returns the “default value” for a type.

impl<'de> Deserialize<'de> for Message

fn deserialize<__D>( __deserializer: __D, ) -> Result<Message, <__D as Deserializer<'de>>::Error>

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl Serialize for Message

fn serialize<__S>( &self, __serializer: __S, ) -> Result<<__S as Serializer>::Ok, <__S as Serializer>::Error>

where __S: Serializer,

Serialize this value into the given Serde serializer.