defmodule MyApp.Eio do
  use Eio.Router

  def connect(session) do
    session |> EIO.Session.send("connect success")
  end

  def message(session, _msg) do
    session |> EIO.Session.send("message received")
    session |> EIO.Session.close
    ...
  end

  def close(_session) do
    ...
  end
end

Plug.Adapters.Cowboy.http MyApp.Eio, []