如何在Phoenix中构建一个客户端订阅特定响应的web-socket服务器？

socket "/socket", MyAppWeb.UserSocket,
  websocket: true,
  longpoll: false

mix phx.gen.socket MySubscription

defmodule MyAppWeb.MySubscription do
  use Phoenix.Channel

  def join("room:" <> room_id, _payload, socket) do
    {:ok, socket}
  end

  def handle_in("subscribe", %{"room_id" => room_id}, socket) do
    # 订阅特定响应的逻辑
    MyAppWeb.Endpoint.subscribe("room:" <> room_id)
    {:ok, socket}
  end

  def handle_info({Phoenix.PubSub, {:message, "room:" <> room_id, payload}}, socket) do
    # 处理特定响应的逻辑
    push(socket, "response", %{room_id: room_id, payload: payload})
    {:noreply, socket}
  end
end

def channel("socket", _params) do
  {:ok, socket} = Phoenix.Presence.track(socket, "user:#{socket.assigns.user_id}", %{
    user_id: socket.assigns.user_id
  })

  [
    {MyAppWeb.MySubscription, "room:*"},
    ...
  ]
end

let socket = new Phoenix.Socket("/socket", {params: {token: window.userToken}})
socket.connect()

let channel = socket.channel("room:123", {})
channel.join()
  .receive("ok", resp => {
    console.log("Joined successfully", resp)
  })
  .receive("error", resp => {
    console.error("Unable to join", resp)
  })

channel.on("response", payload => {
  console.log("Received response", payload)
})