Using Faraday and Typhoeus to post parallel JSON requests to an API endpoint, and asynchronously handling the responses using custom middleware.

endpoint.rb

require 'sinatra'
require 'json'

post '/example' do
  sleep 5
  if request.accept?('application/json')
    content_type :json
    data = JSON.parse request.body.read
    data[:status] = 'OK'
    data.to_json
  end
end

handler.rb

require 'typhoeus/adapters/faraday'

class PosterResponseHandler < Faraday::Response::Middleware
  def call(env)
    # "env" contains the request
    @app.call(env).on_complete do
      # "env" contains the request AND response
      response = {
        request_url: env[:url].to_s,
        response_status: env[:response].status,
        response_body: env[:response].body
      }
      p "PosterResponseHandler: #{response}"
    end
  end
end

output.txt

"queued: {:a=>1}"
"queued: {:b=>2}"
"queued: {:c=>3}"
"PosterResponseHandler: {:request_url=>\"http://0.0.0.0:4567/example\", :response_status=>200, :response_body=>\"{\\\"a\\\":1,\\\"status\\\":\\\"OK\\\"}\"}"
"PosterResponseHandler: {:request_url=>\"http://0.0.0.0:4567/example\", :response_status=>200, :response_body=>\"{\\\"c\\\":3,\\\"status\\\":\\\"OK\\\"}\"}"
"PosterResponseHandler: {:request_url=>\"http://0.0.0.0:4567/example\", :response_status=>200, :response_body=>\"{\\\"b\\\":2,\\\"status\\\":\\\"OK\\\"}\"}"
"complete"

poster.rb

require 'typhoeus'
require 'faraday'
require 'json'
require_relative 'handler'

class Poster
  def initialize
    manager = Typhoeus::Hydra.new(max_concurrency: 100)
    @connection = Faraday.new(parallel_manager: manager) do |builder|
      builder.use PosterResponseHandler
      builder.adapter :typhoeus
    end
  end

  def post_all(data)
    @connection.in_parallel do
      data.each do |d|
        post(d)
        # enqueues request and returns immediately
        p "queued: #{d}"
      end
    end
    # returns when all requests are complete
    p "complete"
  end

  private

  def post(data)
    @connection.post do |req|
      req.url 'http://0.0.0.0:4567/example'
      req.options[:timeout] = 60
      req.headers['Content-Type'] = 'application/json'
      req.body = data.to_json
    end
  end
end

Poster.new.post_all [{a: 1}, {b: 2}, {c: 3}]