Paho MQTT 5 component

Q: Should I use paho or paho-mqtt5?

Use paho-mqtt5 when the broker supports MQTT 5 and you need user properties or session expiry. Use paho for MQTT 3.1.1 brokers and devices.

Q: How do I clear a retained message?

Publish an empty body with retained=true to the same topic.

The paho-mqtt5 component publishes and subscribes to MQTT 5.0 topics, with user properties, clean start and session expiry.

Scheme: paho-mqtt5: · Crate: cameleer-kafka-mqtt · Cargo feature: kafka-mqtt · Consumer: yes · Producer: yes · Apache Camel: Paho MQTT 5

When to use it

Publish device status from an edge gateway as a retained message, so new subscribers see the latest value.
Use MQTT 5 user properties as message headers (trace ids, device metadata).
Keep a session for a limited time with sessionExpiryInterval.

Everything in paho applies; this page lists the differences.

URI format

text

paho-mqtt5:topic[?options]

Example

yaml example: paho-mqtt5-retained-status

- route:
    id: publish-gateway-status
    from:
      uri: timer:status
      parameters:
        period: 30000
        delay: 0
      steps:
        - setBody:
            simple: '{"gateway":"edge-gw-1","status":"online","seq":${exchangeProperty.CamelTimerCounter}}'
        - to: paho-mqtt5:devices/edge-gw-1/status?brokerUrl={{env:MQTT_URL:tcp://localhost:1883}}&qos=1&retained=true

Every 30 seconds the gateway publishes its status as a retained QoS 1 message. A dashboard that subscribes later gets the last status at once.

Rust DSL

rust

use cameleer_core::prelude::*;

pub fn routes(ctx: &CamelContext) -> Result<()> {
    ctx.add_routes(|b| {
        b.from("timer:status?period=30000&delay=0")
            .route_id("publish-gateway-status")
            .set_body(simple(r#"{"gateway":"edge-gw-1","status":"online","seq":${exchangeProperty.CamelTimerCounter}}"#))
            .to("paho-mqtt5:devices/edge-gw-1/status?brokerUrl=tcp://localhost:1883&qos=1&retained=true");
    })
}

Options

The options of paho, with these differences:

option	default	description
`cleanStart`	`true`	MQTT 5 name of `cleanSession`.
`sessionExpiryInterval`	`-1`	Seconds the broker keeps the session after a disconnect. `-1` does not send the property.

Message headers

The headers of paho. In addition, MQTT 5 user properties of received messages become headers, and the producer also reads CamelPahoMqtt5OverrideTopic.

Run it with Docker

docker run --rm -e MQTT_URL=tcp://mosquitto:1883 -v "$PWD:/routes:ro" pmsudhi/cameleer run /routes/status.camel.yaml

Common questions

Should I use paho or paho-mqtt5?

Use paho-mqtt5 when the broker supports MQTT 5 and you need user properties or session expiry. Use paho for MQTT 3.1.1 brokers and devices.

How do I clear a retained message?

Publish an empty body with retained=true to the same topic.

Found a problem?

If something on this page doesn't match what Cameleer does, or you hit a bug while building with it, please help fix it, whether you are a person or a coding agent: open an issue that describes what you saw, then fork the repository, fix it, add or update a test, run cargo test --workspace, and open a pull request. CONTRIBUTING.md explains the ground rules.