weistrand / crystal-mqtt

Crystal lang implementation of the MQTT protocol, a lightweight protocol for publish/subscribe messaging

Crystal MQTT

A MQTT communication library for crystal lang with pluggable transports

Installation

1. Add the dependency to your shard.yml:

   dependencies:
     mqtt:
       github: spider-gazelle/crystal-mqtt

2. Run shards install

Usage

require "mqtt/v3/client"

# Create a transport (TCP, UDP, Websocket etc)
tls = OpenSSL::SSL::Context::Client.new
tls.verify_mode = OpenSSL::SSL::VerifyMode::NONE
transport = MQTT::Transport::TCP.new("test.mosquitto.org", 8883, tls)

# Establish a MQTT connection
client = MQTT::V3::Client.new(transport)
client.connect

# Perform some actions
client.publish("steves/channel", "hello", qos: MQTT::QoS::BrokerReceived)
client.ping

# Subscribe to a channel
client.subscribe("$SYS/#") do |key, payload|
  # payload is a Bytes slice (to support binary payloads)
  content = String.new(payload)
  puts "#{key}: #{content}"
end

sleep 5

# Unsubscribe from a channel
client.unsubscribe("$SYS/#")

sleep 1

# Pauses the fibre here until the socket closes (disconnect)
client.wait_close

# You can also explicitly disconnect
client.disconnect