Wind 🌬️

A pleasant Elixir websocket client library, based on Mint and Mint.WebSocket.

This library was extracted from a high-volume websocket client in an application where speed is a critical priority. Since the implementing code was highly varied, this library aims to provide a minimal framework that doesn't get in the way and provides composable tools to avoid the typical boilerplate.

Note that each connection starts a GenServer instead of all the connections being managed by a dispacting process. This design decision was intentional in order to maintain the speed requirement (and prevent the dispatching process from becoming the bottleneck). However, this may come at a cost of some syntax sugar you might find in other libraries.

Installation

If available in Hex, the package can be installed by adding wind to your list of dependencies in mix.exs:

def deps do
  [
    {:wind, "~> 0.1.0"}
  ]
end

Example

Below is a minimal example to show how you could create a websocket client.

defmodule BinanceMonitor do
  use Wind.Stream, ping_timer: 30_000

  def start_link() do
    uri = URI.new!("wss://data-stream.binance.com/ws")
    Wind.Stream.start_link(__MODULE__, uri: uri)
  end

  def handle_connect(state) do
    message = Jason.encode!(%{method: "SUBSCRIBE", params: ["btcusdt@aggTrade"], id: 1})
    {:reply, {:text, message}, state}
  end

  def handle_frame({:text, message}, state) do
    data = Jason.decode!(message)
    IO.inspect(data)

    {:noreply, state}
  end
end

TODO

• Add telemetry.
• Add additional event handling.