A Crystal library for interacting with GDAX's REST and WebSocket API's.

Add this to your application's shard.yml:

dependencies:
  gdax:
    github: mccallofthewild/gdax

Begin by requiring "gdax".

require "gdax"

Interact with the GDAX REST API

GDAX::Client is derived from HTTP::Client. Use the inherited instance methods, #get, #post, #put and #delete to interact with GDAX's API. Responses are instances of HTTP::Client::Response.

To authenticate, pass named argument, auth to the GDAX::WebSocket with a GDAX::Auth instance. See Authentication for help getting your key, secret, and passphrase.

NOTE: For security purposes, it is recommended that you store your key, secret, and passphrase as environment variables.

e.g.

auth = GDAX::Auth.new ENV["CB-ACCESS-KEY"], ENV["API-SECRET"], ENV["PASSPHRASE"]
client = GDAX::Client.new auth
client.get "/products/BTC-USD/trades" do |response|
  puts response.body_io.gets_to_end
end

To instantiate an unauthenticated Client, simply don't pass the auth argument.

e.g.

client = GDAX::Client.new
client.get "/products" do |response|
  puts response.body_io.gets_to_end
end

See the API Documentation for more information on GDAX::WebSocket.

Interact with the GDAX WebSocket Feed

It's recommended that you spawn a Fiber around each GDAX::WebSocket you instantiate in order to achieve concurrency.

The following setup will give you access to GDAX's public ticker stream.

spawn do
  ws = GDAX::WebSocket.new production: true, subscription: {
    "type" => "subscribe",
    "channels" => [{ "name" => "ticker", "product_ids" => ["ETH-EUR"] }]
  }

  ws.run
end
Fiber.yield

Use the #on method to add event listeners to a GDAX::WebSocket.

Events are based on GDAX's message type's .

#on takes in a String of the event to listen for and a block to call when the event is fired. The block is passed two arguments: the first being the JSON::Any response data from GDAX, and the second being the event itself.

ws.on "subscriptions" do |data, event|
  puts "subscribed!"
end

Though event listeners can be added dynamically on runtime, to avoid missing events, it is recommended that all listeners be added prior to invoking GDAX::WebSocket#run.

e.g.

spawn do
  ws = GDAX::WebSocket.new production: true, subscription: {
    "type" => "subscribe",
    "channels" => [{ "name" => "ticker", "product_ids" => ["ETH-EUR"] }]
  }

  ws.on "subscriptions" do |data, event|
    puts "subscribed!"
  end

  ws.on "ticker" do |data, event|
    puts data["price"] #=> e.g. 264.10000000
  end

  ws.run
end
Fiber.yield

It is possible to authenticate yourself when subscribing to the websocket feed. See the GDAX documentation on the subject.

To authenticate, pass named argument, auth to the GDAX::WebSocket with a GDAX::Auth instance. See Authentication for help getting your key, secret, and passphrase.

NOTE: For security purposes, it is recommended that you store your key, secret, and passphrase as environment variables.

spawn do
  auth = GDAX::Auth.new key: ENV["CB-ACCESS-KEY"], secret: ENV["API-SECRET"], passphrase: ENV["PASSPHRASE"]

  ws = GDAX::WebSocket.new production: true, subscription: {  
    "type" => "subscribe",
    "channels" => [{ "name" => "ticker", "product_ids" => ["ETH-EUR"] }]
  }, auth: auth
  
  ws.on "subscriptions" do |data, event|
    puts "subscribed!"
  end
  ws.run
end

See the API Documentation for more information on GDAX::WebSocket.

1. Fork it ( https://github.com/mccallofthewild/gdax/fork )
2. Create your feature branch (git checkout -b my-new-feature)
3. Commit your changes (git commit -am 'Add some feature')
4. Push to the branch (git push origin my-new-feature)
5. Create a new Pull Request

• McCall Alexander mccallofthewild - creator, maintainer