Crate mqtt_client_blocking 

A small blocking MQTT client on top of stem-mqtt-proto.

No async runtime, no TLS stack of its own: it drives the codec over any Transport (a std::net::TcpStream on a PC or on an ESP32 with ESP-IDF std, a TLS stream, a test double). The caller owns the loop: call Client::poll regularly, it receives messages and keeps the connection alive (PINGREQ) by itself.

use std::net::TcpStream;
use std::time::Duration;
use mqtt_client_blocking::{Client, Options, QoS};

let stream = TcpStream::connect("192.168.1.10:1883")?;
let mut client = Client::connect(stream, Options::new("weather-c6"))?;
client.subscribe("home/+/command", QoS::AtLeastOnce)?;
client.publish("home/c6/status", b"online", QoS::AtLeastOnce, true)?;
loop {
    if let Some(msg) = client.poll(Duration::from_millis(500))? {
        println!("{}: {}", msg.topic, String::from_utf8_lossy(&msg.payload));
    }
}

Scope: QoS 0 and 1 for publishing, QoS 0, 1 and 2 for receiving (a QoS 2 message is delivered once, when the PUBLISH arrives, and completed with PUBREC/PUBCOMP). Publishing at QoS 2 is refused with Error::Unsupported. Reconnecting is the caller’s job: after an error, drop the client and connect again.

Structs

Client

A connected client.

Message

A message received from the broker.

Options

Connection settings.

Stats

Traffic counters (for a status screen).

WillMessage

A message the client sends if the connection is lost without a DISCONNECT.

Enums

Error

What went wrong.

MqttVersion

The MQTT protocol version negotiated for a connection.

QoS

MQTT Quality of Service level.

Constants

DEFAULT_ACK_TIMEOUT

How long Client::connect, Client::publish at QoS 1 and Client::subscribe wait for the broker’s answer.

Traits

Transport

A byte stream with a read timeout, so that Client::poll can wait a bounded time.

Type Aliases

Result