Crate rumqttc

source ·
Expand description

A pure rust MQTT client which strives to be robust, efficient and easy to use. This library is backed by an async (tokio) eventloop which handles all the robustness and and efficiency parts of MQTT but naturally fits into both sync and async worlds as we’ll see

Let’s jump into examples right away

§A simple synchronous publish and subscribe

use rumqttc::{MqttOptions, Client, QoS};
use std::time::Duration;
use std::thread;

let mut mqttoptions = MqttOptions::new("rumqtt-sync", "test.mosquitto.org", 1883);
mqttoptions.set_keep_alive(Duration::from_secs(5));

let (mut client, mut connection) = Client::new(mqttoptions, 10);
client.subscribe("hello/rumqtt", QoS::AtMostOnce).unwrap();
thread::spawn(move || for i in 0..10 {
   client.publish("hello/rumqtt", QoS::AtLeastOnce, false, vec![i; i as usize]).unwrap();
   thread::sleep(Duration::from_millis(100));
});

// Iterate to poll the eventloop for connection progress
for (i, notification) in connection.iter().enumerate() {
    println!("Notification = {:?}", notification);
}

§A simple asynchronous publish and subscribe

use rumqttc::{MqttOptions, AsyncClient, QoS};
use tokio::{task, time};
use std::time::Duration;
use std::error::Error;

let mut mqttoptions = MqttOptions::new("rumqtt-async", "test.mosquitto.org", 1883);
mqttoptions.set_keep_alive(Duration::from_secs(5));

let (mut client, mut eventloop) = AsyncClient::new(mqttoptions, 10);
client.subscribe("hello/rumqtt", QoS::AtMostOnce).await.unwrap();

task::spawn(async move {
    for i in 0..10 {
        client.publish("hello/rumqtt", QoS::AtLeastOnce, false, vec![i; i as usize]).await.unwrap();
        time::sleep(Duration::from_millis(100)).await;
    }
});

loop {
    let notification = eventloop.poll().await.unwrap();
    println!("Received = {:?}", notification);
}

Quick overview of features

  • Eventloop orchestrates outgoing/incoming packets concurrently and handles the state
  • Pings the broker when necessary and detects client side half open connections as well
  • Throttling of outgoing packets (todo)
  • Queue size based flow control on outgoing packets
  • Automatic reconnections by just continuing the eventloop.poll()/connection.iter() loop
  • Natural backpressure to client APIs during bad network

In short, everything necessary to maintain a robust connection

Since the eventloop is externally polled (with iter()/poll() in a loop) out side the library and Eventloop is accessible, users can

  • Distribute incoming messages based on topics
  • Stop it when required
  • Access internal state for use cases like graceful shutdown or to modify options before reconnection

§Important notes

  • Looping on connection.iter()/eventloop.poll() is necessary to run the event loop and make progress. It yields incoming and outgoing activity notifications which allows customization as you see fit.

  • Blocking inside the connection.iter()/eventloop.poll() loop will block connection progress.

§FAQ

Connecting to a broker using raw ip doesn’t work

You cannot create a TLS connection to a bare IP address with a self-signed certificate. This is a limitation of rustls. One workaround, which only works under *nix/BSD-like systems, is to add an entry to wherever your DNS resolver looks (e.g. /etc/hosts) for the bare IP address and use that name in your code.

Re-exports§

Modules§

Structs§

  • AsyncClient
    An asynchronous client, communicates with MQTT EventLoop.
  • Client
    A synchronous client, communicates with MQTT EventLoop.
  • Connection
    MQTT connection. Maintains all the necessary state
  • EventLoop
    Eventloop with all the state of a connection
  • Iter
    Iterator which polls the EventLoop for connection progress
  • MqttOptions
    Options to configure the behaviour of MQTT connection
  • MqttState
    State of the mqtt connection.
  • NetworkOptions
    Provides a way to configure low level network connection configurations
  • Proxy
  • RecvError
    Error type returned by Connection::recv

Enums§

Type Aliases§