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Elixir wrapper for the emqttc library.

emqttc must currently be installed manually as it is not available on hex (yet).


The package can be installed by adding exmqttc and emqttc to your list of dependencies in mix.exs:

def deps do
  [{:exmqttc, "~> 0.5"}, {:emqttc, github: "emqtt/emqttc"}]


Create a callback module:

defmodule MyClient do
  require Logger
  use Exmqttc.Callback

  def init(_params) do
    {:ok, []}

  def handle_connect(state) do
    Logger.debug "Connected"
    {:ok, state}

  def handle_disconnect(state) do
    Logger.debug "Disconnected"
    {:ok, state}

  def handle_publish(topic, payload, state) do
    Logger.debug "Message received on topic #{topic} with payload #{payload}"
    {:ok, state}

You can keep your own state and return it just like with :gen_server.

Start the MQTT connection process by calling start_link/3:

{:ok, pid} = Exmqttc.start_link(MyClient, [], [host: ''], params)

The third argument is a list of emqtt connection options, supporting the following options

  • host: Connection host, charlist, default: 'localhost'
  • port: Connection port, integer, default 1883
  • client_id: Binary ID for client, automatically set to UUID if not specified
  • clean_sess: MQTT cleanSession flag. true disables persistent sessions on the server
  • keepalive: Keepalive timer, integer
  • username: Login username, binary
  • password: Login password, binary
  • will: Last will, keywordlist, sample: [qos: 1, retain: false, topic: "WillTopic", payload: "I died"]
  • connack_timeout: Timeout for connack package, integer, default 60
  • puback_timeout: Timeout for puback package, integer, default 8
  • suback_timeout: Timeout for suback package, integer, default 4
  • ssl: List of ssl options
  • auto_resub: Automatically resubscribe to topics, boolean, default: false
  • reconnect: Automatically reconnect on lost connection, integer (), default false

Params are passed to the init function of your callback module.

You can publish messages to the given PID:

Exmqttc.publish(pid, "test", "foo")

publish/4 also supports passing in QOS and retain options:

Exmqttc.publish(pid, "test", "foo", qos: 2, retain: true)

Further docs can be found at https://hexdocs.pm/exmqttc.