phxsocket

Synchronous phoenix websocket client using callbacks

Phoenix channels

Requirements

websockets

Usage

Import the package

import phxsocket

Create socket client

# endpoint.ex
socket "/socket", MyAppWeb.Socket, websocket: true, longpoll: false

socket = phxsocket.Client("wss://target.url/socket/websocket", {"name": "my name"})

Socket params go to Phoenix.Socket connect/3

Connect and join a channel

# mysocket.ex
defmodule MyAppWeb.Socket do
  use Phoenix.Socket

  channel("channel:*", MyAppWeb.Channel)

  def connect(%{"name" => name} = params, socket, _connect_info) do
    {:ok, socket |> assign(name: name)}
  end

  def id(socket), do: nil
end

defmodule MyAppWeb.Channel do
  use Phoenix.Channel

  def join("channel:" <> room_name, %{"password" => password}, socket) do
    if password == "1234" do
      {:ok, socket}
    else
      {:error, %{reason: "unauthorized"}}
    end
  end
end

if socket.connect(): # blocking, raises exception on failure
  channel = socket.channel("channel:my room", {"password": "1234"})
  resp = channel.join() # also blocking, raises exception on failure

Alternatively

def connect_to_channel(socket):
  channel = socket.channel("channel:my room", {"password": "1234"})
  resp = channel.join()

socket.on_open = connect_to_channel
connection = socket.connect(blocking=False)

connection.wait() # blocking, raises exception on failure

Reconnect on disconnection

socket.on_close = lambda socket: socket.connect()

Subscribe to events

def do_something(payload):
  content = payload["content"]

channel.on("message", do_something)

MyAppWeb.Endpoint.broadcast("channel:my room", "message", %{"content": "hello"})

Push data to a channel

defmodule MyAppWeb.Channel do
...
def handle_in("message", %{"content" => content}, socket) do
  IO.inspect("received from #{socket.assigns.name}: #{content}")
  {:reply, {:ok, "hello"}, socket}
end

channel.push("message", {"content": "hello"})

This throws away the reply if the return value of handle_in is :reply

Push data and wait for a response

message = channel.push("message", {"content": "hello"}, reply=True)
payload = message.wait_for_response() # blocking

Push data and react to the response with a callback

def response(payload):
  print(payload["status"]) # ok
  print(payload["response"]) # hello

channel.push("message", {"content": "hello"}, response)

Leave a channel

channel.leave()

Disconnect

socket.close()