Application and basic MQTT subscriber

lib/neon_vertigo_service.ex

@@ -3,16 +3,18 @@ defmodule NeonVertigoService do
   Documentation for `NeonVertigoService`.
   """
 
-  @doc """
-  Hello world.
+  use Application
 
-  ## Examples
+  @impl true
+  def start(_start_type, _start_args) do
+    children = [
+      # %{id: :emqtt, start: {:emqtt, :start_link, [[{:owner, self()}, {:username, "artemis"}, {:password, "artemis"}]]}}, 
+      {NeonVertigoService.Mqtt, [{}]}
+    ]
 
-      iex> NeonVertigoService.hello()
-      :world
+    {:ok, _spid} = Supervisor.start_link(children, strategy: :one_for_one)
+    # {:ok, mqtt_pid} = Supervisor.start_child(spid, %{id: :emqtt, start: {:emqtt, :start_link, [[{:owner, self()}, {:username, "artemis"}, {:password, "artemis"}]]}})
+    # {:ok, _} = Supervisor.start_child(spid, {NeonVertigoService.Mqtt, [{mqtt_pid}]})
 
-  """
-  def hello do
-    :world
   end
 end

lib/neon_vertigo_service/mqtt.ex

@@ -0,0 +1,25 @@
+defmodule NeonVertigoService.Mqtt do
+  use GenServer
+
+  def start_link(_) do
+    GenServer.start_link(__MODULE__, {})
+  end
+  
+  def init(_) do
+    mqtt_config = Application.fetch_env!(:neon_vertigo_service, :mqtt_params)
+    {:ok, mqtt_pid} = :emqtt.start_link([{:owner, self()} | mqtt_config]) 
+    {:ok, _mqtt_props} = :emqtt.connect(mqtt_pid)
+    Process.link(mqtt_pid)
+
+    :emqtt.subscribe(mqtt_pid, %{}, [{"$share/neon-vertigo-service/test/+", [{:qos, 1}]}])
+
+    {:ok, {mqtt_pid}}
+  end
+
+  # Handling MQTT messages
+  def handle_info({:publish, msg}, state) do
+    IO.puts("Received message") 
+    IO.inspect(msg)
+    {:noreply, state}
+  end
+end