CODEWITHSUNDEEP
elixir
Peter
Peter

Reputation: 43

Confusion about run time and libraries in Elixir

I'm trying to use an MQTT library in elixir known as Tortoise. Whenever I use iex -S mix I can get the sending of messages to work. However when I use mix start to begin my start task the program will not work. I'm get an unknown registry: Tortoise.Registry error.

I can start the supervisor for Tortoise without error, it is when I try starting a child process for that process with Tortoise.Supervisor.start_child that I get the error.

defmodule Mqtt.Begin do
require Tortoise
def start do

opts = [strategy: :one_for_one, name: Mqtt.Begin]
  {:ok, pid} = Tortoise.Supervisor.start_link(opts)

      {:ok, _} =
    Tortoise.Supervisor.start_child(Mqtt.Begin, [
      client_id: :a,
      handler: {Mqtt.Handler, [name: :a]},
      server: {Tortoise.Transport.Tcp, host: 'localhost', port: 1883},
      subscriptions: [{"share/share-group/bar", 0}] ])

When using extern libraries in elixir is the entire library created with deps.compile? Or do I need to do something further?

Upvotes: 0

Views: 170

Answers (1)

Konstantin Zolotarev
Konstantin Zolotarev

Reputation: 622

Seems that this is because of erlang code loading principals When you start your application using iex -S mix erlang starts it into interactive mode and automatically loads all modules.

mix start (you should call mix run) seems to start your application in embedded mode In embedded mode, code is loaded at start-up according to a boot script.

http://erlang.org/doc/reference_manual/code_loading.html#code-loading

To make it work you have to add :tortoise into your application list in mix.exs :

def application do
    [
      extra_applications: [:logger, :ssl, :tortoise],
      mod: {Your.App, []}
    ]
end

Upvotes: 1

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