Connect with Rust

Below is an example using the paho.mqtt.rust crate with the TOKEN authentication mode configured on a Broker.

The example below creates a simple subscriber, sends a message to the configured topic, and waits until the message is received before exiting.

Make sure to set the BROKER_URI (e.g. mqtts://YOUR-BROKER.YOUR-NAMESPACE.cloudflarepubsub.com), BROKER_TOKEN (a valid auth token), and BROKER_TOPIC environmental variables before running the example program.


# in your Cargo.toml
paho-mqtt = "0.11.1"

Create a file called example.rs with the following content, and use cargo run to build and run the example:


use paho_mqtt::*;
use std::thread; fn main() {    // Specify MQTT broker hostname: <broker name>.<namespace>.cloudflarepubsub.com    let uri = std::env::var("BROKER_URI").expect("URI must be set");     // Your JWT token    let jwt = std::env::var("BROKER_TOKEN").expect("JWT must be set");     // Specify a topic name    let topic = std::env::var("BROKER_TOPIC").expect("Topic must be set");     // Configure the MQTT client    let client_opts = CreateOptionsBuilder::new()        .mqtt_version(MQTT_VERSION_5)        .server_uri(uri)        .finalize();     // Connect options    let options = ConnectOptionsBuilder::new()        .ssl_options(SslOptions::default())        .clean_start(true)        .password(jwt)        .finalize();     // Create the MQTT client    let cli = Client::new(client_opts).expect("Error creating client");     // Connect to your broker    cli.connect(options).expect("Error connecting to broker");     // Message receiver    let rx = cli.start_consuming();     // Subscribe to a topic    cli.subscribe(&topic, 0)        .expect("Error subscribing to topic");     // Start waiting for messages    let reader = thread::spawn(move || match rx.recv().expect("Error receiving message") {        Some(message) => {            println!("{:?}", message);        }        None => {}    });     // Publish a message!    cli.publish(Message::new(topic, "My first MQTT message", 0))        .expect("Error publishing");     // Wait until we have received our message    let _ = reader.join();     // Good-Bye    cli.disconnect(DisconnectOptions::default())        .expect("Error disconnecting");
}