Standalone Phoenix.PubSub

Phoenix Forum Questions / Help
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1

Does anybody know how to use phoenix_pubsub as a standalone component?

I’d like to use it as a generic pubsub to communicate between some umbrella child applications.

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2

I did some digging around in the Phoenix channel code and was able to put this together.

Hopefully, it helps someone else.

defmodule Commander.Server do
  use GenServer

  #
  # client
  #

  def dispatch(event) do
    Phoenix.PubSub.broadcast(Commander.PubSub, get_event_name(event), event)
  end

  def subscribe(subscriber, event) do
    GenServer.start_link(__MODULE__, { subscriber, event })
  end

  #
  # callbacks
  #

  def init({ subscriber, event }) do
    Phoenix.PubSub.subscribe(Commander.PubSub, event)

    { :ok, { subscriber } }
  end

  def handle_info(msg, { subscriber } = state) do
    subscriber.handle(msg)

    { :noreply, state }
  end

  #
  # private
  #

  defp get_event_name(event) do
    event.__struct__
    |> to_string()
    |> String.replace("Elixir.", "")
  end
end
6 Likes
3

It has been a while, but according to the latest Phoenix.PubSub (1.1.1), it also “also provides an API for direct usage”:
https://hexdocs.pm/phoenix_pubsub/Phoenix.PubSub.html#module-direct-usage

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