appsync_subscribe.rb

require "json"
require "websocket-eventmachine-client"
require "securerandom"
require 'date'
require "base64"

API_HOST = "CHANGEME.appsync-api.ap-northeast-1.amazonaws.com"
API_KEY = "da2-CHANGEME"
REAL_TIME_HOST = API_HOST.gsub("appsync-api","appsync-realtime-api")

def authorization(options={include_user_agent: true})
  #timestamp = Time.now.to_datetime.rfc3339
  timestamp = `TZ=UTC date +%Y%m%dT%H%M%SZ`.chomp
  hash = {
    host: API_HOST,
    "x-amz-date": timestamp,
    "x-api-key": API_KEY
  }
  hash[:"x-amz-user-agent"] = "aws-amplify/2.2.2 js" if options[:include_user_agent]
  hash
end

def gql_message(gql_query, gql_variables={})
  uuid = SecureRandom.uuid
  data = {query: gql_query, variables: gql_variables}
  {
    id: uuid,
    payload: {
      data: data.to_json,
      extensions: { authorization: authorization }
    },
    type: "start"
  }
end

def base64authorization
  auth_for_connect = authorization(include_user_agent: false)
  Base64.strict_encode64(auth_for_connect.to_json)
end

SERVER_URL = "wss://#{REAL_TIME_HOST}/graphql?header=#{base64authorization}&payload=e30="
HEADERS = { "Sec-WebSocket-Protocol": "graphql-ws"}

puts "Connecting to: #{SERVER_URL}"

def start_event_loop

  EM.run do
    trap("TERM") { stop }
    trap("INT") { stop }
    ws = WebSocket::EventMachine::Client.connect(uri: SERVER_URL, headers: HEADERS, debug: true, secure: true )
    ws.onopen do
      puts "Connected"
    end

    ws.onmessage do |msg, type|
      puts "Received message: #{msg}"
      #MESSAGES.push(msg)
    end

    ws.onclose do |code, reason|
      puts "Disconnected with status code: #{code}"
    end

    EventMachine::Timer.new(5) do
      ws.send gql_message("subscription { inbox(to: \"Arek\") {to, body}}").to_json
      ws.send gql_message("subscription { createdEvent {id, name}}").to_json
      #ws.send gql_message("{hello { greeting }}").to_json
    end

    def stop
      puts "Terminating connection"
      EventMachine.stop
    end
  end
end

start_event_loop