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

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.Client, ping_timer: 30_000

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