Messages

Each message reports the MQTT 5 properties it rides: a delivery the response topic and correlation data, a published message the correlation data.

The crate carries two headers in the protocol's own properties: correlation-id in Correlation Data and reply-to in Response Topic. The message binding describes them, each as a string. A message a subscription reads reports both. A requester sets the response topic on its own request, and a message a service publishes is not that request. So a message an Out slot or a reply sends reports the correlation data alone. Where a reply goes is the operation's reply object, and a reply named per request reports its address there.

The payload format indicator stays out of the binding. It follows the media type one message carries in its content-type header, which no declaration knows. The document reports the media type of the position's codec in the contentType the core fills.

Example

Telemetry reports correlationData and responseTopic; Alert, which the slot publishes, reports correlationData only.

Macros

examples/mqtt_asyncapi.rs

/// What every device publishes; a subscription reads it.
#[derive(Debug, Deserialize, Serialize, Outgoing)]
struct Telemetry {
    device: String,
    temperature: f64,
}

/// What the service publishes through its slot when a device runs hot.
#[derive(Debug, Serialize, Outgoing)]
#[outgoing(name = "alerts/overheat")]
struct Alert {
    device: String,
}

Manual

examples/manual/mqtt_asyncapi.rs

/// What every device publishes; a subscription reads it.
#[derive(Debug, Deserialize, Serialize, Outgoing, JsonSchema)]
#[schemars(crate = "ruststream::schemars")]
struct Telemetry {
    device: String,
    temperature: f64,
}

/// What the service publishes through its slot when a device runs hot.
#[derive(Debug, Serialize, Outgoing, JsonSchema)]
#[schemars(crate = "ruststream::schemars")]
#[outgoing(name = "alerts/overheat")]
struct Alert {
    device: String,
}