erlang-mqtt's Introduction

erlang-mqtt

MQTT Protocol library for Erlang/Elixir. This library provides the low level building blocks for MQTT.

Protocol

mqtt_packet exposes an encode function and a decode function to convert binaries to MQTT packets as defined in mqtt/include/mqtt_packet.hrl

Client

mqtt_client provides a simple client for MQTT. Currently this client only supports QoS 0 messages.

Example Erlang client usage

ok = application:ensure_all_started(mqtt),

{ok, Connection, false} = mqtt_client:connect(#{
    transport => {tcp, #{host => "localhost"}}
}),

Topic = <<"/test">>,
{ok, [{Topic, 0}]} = mqtt_client:subscribe(Connection, [{topic, 0}]),

ok = mqtt_client:publish(Connection, Topic, <<"Hello">>),
receive
    {mqtt_client, Connection, {publish, Topic, Message, _}} ->
        io:format("Got ~s published on ~s~n", [Message, Topic]
end.

Example Elixir client usage

{:ok, connection, false} = MQTT.Client.connect(%{
    transport: {:tcp, %{host: "localhost"}}
})

topic = "/test"
{:ok, [{^topic, 0}]} = MQTT.Client.subscribe(connection, [{topic, 0}])

:ok = MQTT.Client.publish(connection, topic, "Hello")
receive do
    {:mqtt_client, ^connection, {:publish, ^topic, message, _}} ->
        IO.puts "Got #{message} published on #{topic}"
end

Server

mqtt_server provides a server behaviour for MQTT. A server would implement the mqtt_server behaviour, and would then be able to accept MQTT connections from clients. Currently this server only supports QoS 0 messages.

TODO

Add support for QoS 1 and 2

We need to add support for QoS 1 and 2 messages, this would require implementing a storage module in order to persist messages until they get acknowledged by the broker.

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erlang-mqtt's Issues

Callbacks not called when disconnected in mqtt_client

The mqtt_client is trying to be too smart and avoids calling the callbacks when it is disconnected. This is a surprising behaviour and should be changed.

Documentation needed for MQTT.Server

I'm having trouble running the server. I'm running mix test with the following test in it:

defmodule MyMqttServerTest do
  use ExUnit.Case
  alias MQTT.Client

  test "greets the world" do
    {:ok, connection, false} = MQTT.Client.connect(%{
        transport: {:tcp, %{host: "localhost", port: 1883}},
        client_id: UUID.uuid1()
    })

    topic = "/hello"
    message = "hello"

    {:ok, [{^topic, 0}]} = Client.subscribe(connection, [{topic, 0}])
    :ok = Client.publish(connection, topic, message)

    assert_receive {:mqtt_client, ^connection, {:publish, ^topic, ^message, _}}

    :ok = Client.disconnect(connection)
  end
end

Child process:

%{
  id: MyMqttServer,
  type: :worker,
  start: {MyMqttServer, :start_link, [[:hello]]}
}

defmodule MyMqttServer do
  use MQTT.Server

  def start_link(state) do
    GenServer.start_link(__MODULE__, state, name: __MODULE__)
  end

  def init(stack) do
    {:ok, stack}
  end

  def init(stack, _) do
    {:ok, stack}
  end
  
  def handle_subscribe(_topic, _qos, state) do
    IO.inspect("I never get output")
    {:ok, state}
  end
end

It seems to be running but I can't seem to override the fun? I'm still relatively new to this so apologies if this is a simple question.

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kopera / erlang-mqtt Goto Github PK

erlang-mqtt's Introduction

erlang-mqtt

Protocol

Client

Example Erlang client usage

Example Elixir client usage

Server

TODO

Add support for QoS 1 and 2

erlang-mqtt's People

Contributors

Stargazers

Watchers

Forkers

erlang-mqtt's Issues

Callbacks not called when disconnected in mqtt_client

Documentation needed for MQTT.Server

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