Use of gun from elixir

websockets-with-gun.ex

defmodule Transport do

  def connect(params) do
    hostname = params.hostname
    port     = params.port
    path     = params.path
    timeout  = params.connection_timeout
    {:ok, conn}  = :gun.open(hostname, port)
    {:ok, :http} = :gun.await_up(conn)
    :gun.ws_upgrade(conn, path)
    receive do
      {:gun_ws_upgrade, ^conn, :ok, _} ->
        established(conn)
    after timeout ->
      raise "timeout"
    end
  end

  def established(conn) do
    receive do
      {:gun_down, ^conn, _, _, _, _} ->
        IO.puts "Transport: received down event"
      {:gun_ws, ^conn, {:binary, data}} ->
        IO.puts "Transport: received: #{inspect data}"
        established(state)
      {:send, data} ->
        IO.puts "Transport: sending frame #{inspect data}"
        :gun.ws_send(conn, {:binary, data})
        established(conn)
      :shutdown ->
        IO.puts "Transport: good bye!"
        :gun.shutdown(conn)
      _msg -> 
        IO.puts "Transport: unhandled message: #{inspect _msg}"
        established(conn)
    end
  end

end