Hi!

I read Supervisor.Spec – Elixir v1.4.2 multiple times, but I still don’t understand what’s different between a worker and a supervisor? Is it just that the supervisor is used to supervise? And the worker should be doing work?

If that is the case, then the skeleton code below should be a worker rather than a supervisor?

defmodule Notifier do
  def init(state) do
    Notifier.schedule_send_push_notifications
    {:ok, state}
  end

  def handle_info(:send_push_notifications, state) do
    {:ok, pid} = Task.start_link(fn -> Notifier.send_push_notifications(self(), state[:last_notified_at]) end)
    %{state | notifier_task_pid: pid}
  end

  def schedule_send_push_notifications() do
    Process.send_after(self(), :send_push_notifications, 30*1000)
  end

  def send_push_notifications(from, last_notified_at) do
    # send push notifications
    # reply with correct last_notified_at
  end
end

The Notifier process is responsible for starting a task when it’s time to send the push notifications, but beyond that, this process holds some state and passively waits for messages. It feels like my understanding of workers vs supervisors is flawed.

Thanks!
François