Elixir: Why Processes Trump Objects

Over the past quarter-century, we’ve witnessed the rise and widespread adoption of object-oriented (OO) languages. We bought into the promise that objects would solve all our technical challenges. That class hierarchies would bring order to our tangled messes. But something has gone horribly wrong.

The technical requirements of our software continue to rise, and our trusty OO languages aren’t keeping up. They’re unable to climb the ladder of complexity. How do we scale the complexity of a system without being crushed by the cognitive overhead it takes to keep it all in our head?

Kevin Rockwood explores how process-oriented architecture embodies the principles that object-oriented architecture always intended and explains how you can use processes to tackle complex problems that other languages could only dream about. For the past 30 years, Erlang, along with its pioneering runtime, has been quietly fighting alongside its OO brethren. Although its approach is drastically different from the OO languages of today, it’s actually much more closely aligned to object-oriented guiding principles. Now, Elixir is catapulting the pioneering approach of Erlang into the mainstream. The wave is approaching. Choose processes over objects, and embrace the magic of Elixir.

Transcript

1. teamgaslight.com
   Elixir
   Why processes trump objects
   @kevinrockwood
   Kevin Rockwood
   

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2. Elixir
   

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3. I work for Gaslight in Cincinnati
   Hi, I'm Kevin
   

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4. What is Object Oriented?
   

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5. • Classes
   • Methods
   • Instances
   • Inheritance
   

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6. • Java
   • Python
   • Ruby
   

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11. This is a lot like the internet
    

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12. ALAN KAY
    “I thought of objects being like biological cells
    and/or individual computers on a network, only
    able to communicate with messages”
    

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14. • Distributed
    • Fault-tolerant
    • Real-time
    • Highly available
    What Ericsson Needs:
    

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15. Erlang / OTP Framework
    

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16. • Dynamic
    • Compiled
    • Functional
    • Immutable
    • Everything is a Processtm
    Erlang Language
    

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17. • Implements the actor model with Erlang processes
    • Libraries for managing the process lifecycle
    • Hot code swapping
    • Data persistance
    OTP Framework
    

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18. Switch
    Phone
    Phone
    Phone
    Phone
    Switch
    Phone
    Phone
    Phone
    Switch
    

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19. Server
    Browser
    iOS
    Android
    PI
    Server
    Arduino
    Browser
    iOS
    Server
    

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21. Elixir
    

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22. Processes Communicate Via Messages
    

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23. Processes Have State
    > {:ok, pid} = MyProcess.start()
    > MyProcess.push(pid, "Hello World")
    []
    []
    ["Hello World"]
    

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24. Processes Have State
    defmodule MyProcess do
    def init() do
    {:ok, []}
    end
    def handle_call({:push, message}, state) do
    {:ok, [message | state]}
    end
    end
    > {:ok, pid} = MyProcess.start_link
    // state = []
    > MyProcess.push(pid, "Hello World")
    // state = ["Hello World"]
    

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25. Let's Build a Web Crawler
    

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27. Web Server
    Socket Manager
    Crawlers
    Crawler Registry
    Connection Pool
    What Do We Need?
    App 1
    App 2 Umbrella
    

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28. Browser
    crawl(example.com) push("/page_1")
    ...
    Phoenix
    Channel
    Crawler
    Connection
    Pool
    

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29. Supervisor
    Registry
    Connection
    Pool
    Crawler
    github.com
    Crawler
    oscon.com
    Crawler
    example.com
    

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30. // Phoenix Channel
    def handle_in("crawl", %{"url" => url}, socket) do
    Crawler.start(url)
    receive do
    {:page, new_page} -> push(socket, "new_page", new_page)
    {:link, new_link} -> push(socket, "new_link", new_link)
    end
    end
    

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31. %{
    root: "example.com",
    pages: %{
    "example.com" => %{id: 1}
    "example.com/page_1" => %{id: 2}
    "example.com/page_3" => %{id: 3}
    },
    links: [
    %{target: 1, source: 2},
    %{target: 2, source: 1},
    %{target: 2, source: 3},
    %{target: 3, source: 1},
    ]
    }
    Crawler
    Connection
    Pool
    

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32. Demo!
    

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33. What is Object Oriented?
    

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34. • Objects should be completely isolated
    • Objects should only communicate via message passing
    • Objects should be fault tolerant
    What is Object Oriented?
    

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35. • Processes should be completely isolated
    • Processes should only communicate via messaging
    • Processes should be fault tolerant
    What is Object Oriented?
    

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36. Processes are what OO
    always intended
    

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37. teamgaslight.com
    Elixir
    Why processes trump objects
    @kevinrockwood
    Kevin Rockwood
    

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