[BRUG Minsk, May 2017] Action Cable. Making Better

Video: https://www.youtube.com/watch?v=D7TZH3_gh6M

Links:

- Action Cable PRs – https://github.com/rails/rails/pulls?q=is%3Aopen+is%3Apr+author%3Apalkan+label%3Aactioncable

- AnyCable – http://anycable.io

- LiteCable – https://github.com/palkan/litecable

- ACLI – https://github.com/palkan/acli

- Plezi – http://www.plezi.io

Transcript

3. Evil Martians
4. Evil Martians
5. What is Action Cable?
6. Action Cable RailsConf 2015 April, 21
7. Action Cable RailsConf 2015
8. Action Cable in a Nutshell Server Client WebSocket Client WebSocket stream C Broadcaster stream B stream A stream B channel X channel Y channel Z
9. Action Cable Channel class AnswersChannel < ApplicationCable::Channel def subscribed reject_subscription unless current_user.admin? end def follow(params) stream_from "questions/#{params['id']}" end end
10. The Good Parts
11. Good Parts • Easy configuration
12. Good Parts • Easy configuration • Application logic access through channels
13. Good Parts • Easy configuration • Application logic access through channels • JavaScript client that just works
14. Bad Parts?
15. Performance
16. Memory Cable
17. Memory Cable 20k connections MB 0 375 750 1 125 1 500 1 875 2 250 2 625 3 000 Go Erlang ActionCable (2x) ActionCable (16x)
18. WebSocket Shootout
19. WebSocket Shootout Client Server broadcast to all message send message back
20. WebSocket Shootout Broadcast RTT 0s 1s 2s 3s 4s 5s 6s 7s 8s 9s 10s Number of connections 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000 Go Erlang ActionCable Running on AWS EC2 c3.4xlarge (16 vCPU, 30 GiB RAM)
21. WebSocket Shootout
22. Testing
23. Testing Cable
24. Extensibility
25. • Server Abstraction Extended Cable
26. • Server Abstraction • Protocol Extensions (e.g. serialization, authentication, presence feature) Extended Cable
27. Other • Fallbacks / Transport • Rails-ness • Consistency
28. Consistency
29. Consistency?
30. How to Make it Better?
31. Testing Cable , 2016
32. Testing Cable class ServiceTest < ActionCable::TestCase def test_assert_transmited_message Service.broadcast 'messages', 'hi!' assert_broadcast_on('messages', text: 'hi!') end def test_assert_broadcast_on_again assert_broadcast_on('messages','h!') do Service.broadcast 'messages', text: 'h!' end end end
33. Testing Cable class ChannelTest < ActionCable::Channel::TestCase def test_subscribed_with_room_number subscribe room_number: 1 assert subscription.confirmed? assert "chat_1", streams.last end def test_perform_speak subscribe room_number: 1 perform :speak, message: "Hello" assert_equal "Hello", transmissions.last["message"]["text"] end end
34. PRs Cable
35. PRs Cable
36. AnyCable
38. Server Channels Streams Client (Protocol) Action Cable AnyCable
39. Server Channels Streams Client (Protocol) Separation of Concerns Action Cable AnyCable
40. AnyCable
41. gRPC
42. gRPC = Google RPC
43. gRPC = Universal RPC Framework
44. gRPC = protobuf + HTTP/2
45. AnyCable Servers anycable-go erlycable
46. Memory Cable 20k connections MB 0 500 1 000 1 500 2 000 2 500 3 000 3 500 4 000 anycable-go erlycable ActionCable
47. Action Cable CPU
48. anycable-go CPU
49. erlycable CPU
50. WebSocket Shootout Broadcast RTT 0s 1s 2s 3s 4s 5s 6s 7s 8s 9s 10s Number of connections 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000 ActionCable anycable-go erlycable Running on AWS EC2 c3.4xlarge (16 vCPU, 30 GiB RAM)
51. Compatibility Feature Status Connection Identifiers + Connection Request (cookies, params) + Disconnect Handling + Subscribe to channels + Parameterized subscriptions + Unsubscribe from channels + Subscription Instance Variables - Performing Channel Actions + Streaming + Custom stream callbacks - Broadcasting +
52. Action Cable Channel class ChatChannel < ApplicationCable::Channel def subscribed stream_from "chat_#{chat_id}" do |msg| if msg['sent_at'].present? delay = Time.now.to_f - msg['sent_at'] logger.info "Message delay #{delay}s" end transmit msg end end end
53. PRs Cable
54. WebSocket Shootout Broadcast RTT 0s 1s 2s 3s 4s 5s 6s 7s 8s 9s 10s Number of connections 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000 ActionCable Patch 1 Running on AWS EC2 c3.4xlarge (16 vCPU, 30 GiB RAM)
55. Where To anycable.io github.com/anycable twitter.com/any_cable gitter.im/anycable
56. PRs Cable
57. Server Adapter # config/application.rb 
 # specify server adapter config.action_cable.server = :plezi # or config.action_cable.server = :any_cable
58. plezi.io github.com/boazsegev/iodine Plezi
59. LiteCable
60. • Rails-free Action Cable • No deps (even ActiveSupport) • Compatible with AnyCable LiteCable
61. LiteCable module Chat # ... class Channel < LiteCable::Channel::Base identifier :chat def subscribed stream_from "chat_#{chat_id}" end end end run Rack::Builder.new do map '/cable' do use LiteCable::Server::Middleware, connection_class: Chat::Connection run proc { |_| [200, {}, ['']] } end end
62. LiteCable github.com/palkan/litecable
63. • Testing Support PRs • AnyCable for Performance • LiteCable for non-Rails • ACLI for development/testing What We Have
64. • Action Cable CLI • mRuby • Download'n'Run ACLI
65. ACLI
66. What's Next?
67. History Stream class ChatChannel < ApplicationCable::Channel def subscribed stream_from "chat_#{id}", history: { time: 5.minutes } end end class ChatChannel < ApplicationCable::Channel def subscribed stream_from "chat_#{chat_id}", history: { size: 100 } end end
68. Presence class ChatChannel < ApplicationCable::Channel def subscribed stream_from "chat_#{id}", presence: { user_id: user_id } end end // js client cable.subscriptions.create( { channel: 'chat', id: roomId }, { presenceUpdated: function(diff) { … } } )
69. cult of martians.com
70. Let's make Action Cable suck less! Vladimir Dementyev evilmartians.com @palkan @palkan_tula