[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

1. View Slide

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3. Evil Martians
   

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4. Evil Martians
   

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5. What is
   Action Cable?
   

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6. Action Cable
   RailsConf 2015 April, 21
   

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7. Action Cable
   RailsConf 2015
   

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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
   

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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
   

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10. The Good Parts
    

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11. Good Parts
    • Easy configuration
    

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12. Good Parts
    • Easy configuration
    • Application logic access through
    channels
    

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13. Good Parts
    • Easy configuration
    • Application logic access through
    channels
    • JavaScript client that just works
    

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14. Bad Parts?
    

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15. Performance
    

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16. Memory Cable
    

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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)
    

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18. WebSocket Shootout
    

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19. WebSocket Shootout
    Client
    Server
    broadcast
    to all
    message
    send message back
    

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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)
    

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21. WebSocket Shootout
    

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22. Testing
    

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23. Testing Cable
    

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24. Extensibility
    

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25. • Server Abstraction
    Extended Cable
    

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26. • Server Abstraction
    • Protocol Extensions (e.g.
    serialization, authentication,
    presence feature)
    Extended Cable
    

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27. Other
    • Fallbacks / Transport
    • Rails-ness
    • Consistency
    

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28. Consistency
    

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29. Consistency?
    

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30. How to Make it
    Better?
    

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31. Testing Cable
    , 2016
    

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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
    

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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
    

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34. PRs Cable
    

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35. PRs Cable
    

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36. AnyCable
    

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37. View Slide

38. Server
    Channels
    Streams
    Client (Protocol)
    Action Cable AnyCable
    

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39. Server
    Channels
    Streams
    Client (Protocol)
    Separation of Concerns
    Action Cable AnyCable
    

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40. AnyCable
    

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41. gRPC
    

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42. gRPC =
    Google RPC
    

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43. gRPC =
    Universal RPC
    Framework
    

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44. gRPC =
    protobuf + HTTP/2
    

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45. AnyCable Servers
    anycable-go
    erlycable
    

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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
    

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47. Action Cable CPU
    

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48. anycable-go CPU
    

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49. erlycable CPU
    

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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)
    

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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 +
    

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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
    

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53. PRs Cable
    

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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)
    

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55. Where To
    anycable.io
    github.com/anycable
    twitter.com/any_cable
    gitter.im/anycable
    

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56. PRs Cable
    

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57. Server Adapter
    # config/application.rb
    

    # specify server adapter
    config.action_cable.server = :plezi
    # or
    config.action_cable.server = :any_cable
    

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58. plezi.io
    github.com/boazsegev/iodine
    Plezi
    

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59. LiteCable
    

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60. • Rails-free Action Cable
    • No deps (even ActiveSupport)
    • Compatible with AnyCable
    LiteCable
    

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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
    

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62. LiteCable
    github.com/palkan/litecable
    

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63. • Testing Support PRs
    • AnyCable for Performance
    • LiteCable for non-Rails
    • ACLI for development/testing
    What We Have
    

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64. • Action Cable CLI
    • mRuby
    • Download'n'Run
    ACLI
    

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65. ACLI
    

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66. What's Next?
    

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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
    

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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) { … }
    }
    )
    

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69. cult of martians.com
    

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70. Let's make Action Cable
    suck less!
    Vladimir Dementyev
    evilmartians.com
    @palkan
    @palkan_tula
    

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