Crate gmqtt_client[−][src]
Expand description
Simple MQTTv5 client
gmqtt-client
is pure-rust implementation of an mqtt 5.0 protocol.
Main features:
- Auto reconnect
- Resubscribe topics after reconnect
- Message queue supports Message Expiry Interval and Retain flag
Messages queue
When disconnected from mqtt broker, messages are kept in queue on RAM. If client disconnects from MQTT broker, messages will be kept in queue in RAM.
Messages with Message Expiry Interval are counted down and dropped when expired.
For example, if message is sent with message_expiry_interval = 60 (seconds)
and client reconnects after 15 seconds, the message will be send with message_expiry_interval = 45
to broker.
Messages with Retain flag and the same topic are replaced in queue. Only last retained message is kept and send to broker.
Those two features help to reduce memory usage when client is offline for long time.
Basic Example
use std::time::Duration;
use tokio::runtime;
use gmqtt_client::{MqttClientBuilder, QoS};
use url::Url;
use serde::Serialize;
#[derive(Serialize)]
struct Event {
id: u32,
}
fn main() -> anyhow::Result<()> {
let (mqtt_client, mqtt_worker) = MqttClientBuilder::new(Url::parse("tcp://localhost:1883")?)
.on_message_owned_callback(|message, instant| {
println!("Message: {:?} received {} us ago", message, instant.elapsed().as_micros());
})
.subscribe("client/example/receive", QoS::AtLeastOnce)
.build();
let worker_runtime = runtime::Builder::new_multi_thread()
.enable_all()
.worker_threads(1)
.build()?;
worker_runtime.spawn(async { mqtt_worker.run().await });
let payload = Event {
id: 10
};
mqtt_client.publish_json(
"client/example/publish",
&payload,
false,
QoS::AtLeastOnce,
Some(Duration::from_secs(10)),
)?;
std::thread::park();
Ok(())
}
Run Example
sudo apt-get install mosquitto mosquitto-clients
cargo run --example client
mosquitto_sub -t 'client/example/publish' --pretty -F '%J'
mosquitto_pub -t 'client/example/receive' -m "hello" -q 1 -V 5 -r -D publish message-expiry-interval 5
for i in {0..1000}; do mosquitto_pub -t 'client/example/receive' -m "$i" -q 1 -V 5 -r -D publish message-expiry-interval 5; echo "sending $i"; done
Modules
Structs
Enums
Quality of service