example.ex

defmodule SomeModule do
  def start(host, options) do
    # We are assuming SomeSup has been already started somewhere
    # (ideally in a supervision tree).
    {:ok, child_pid} = SomeSup.attach_to(SomeSup, host, options)
  end
end

defmodule SomeSup do
  use Supervisor

  def attach_to sup, host, options do
    Supervisor.start_child(sup, [host, options])
  end

  def start_link do
    Supervisor.start_link(__MODULE__, [], name: __MODULE__)
  end

  def init [] do
    supervise([worker(SomeWorker, [], restart: :temporary)], strategy: :simple_one_for_one)
  end
end

defmodule SomeWorker do
  use GenServer

  alias :gproc, as: GProc

  def start_link host, options do
    GenServer.start_link(__MODULE__, [host, options], name: {:via, GProc, {:n, :l, :conv_id}})
  end

  def init [host, options] do
    #Let GProc know that this is a conversation
    GProc.reg({:p, :l, :conversation})
    {:ok, []}
  end
end