Using RethinkDB with Tornado & EventMachine

This talk demonstrates how to use the Tornado and EventMachine integration in RethinkDB's Python and Ruby drivers. It also shows how to build realtime apps in Ruby with RethinkDB and Faye.

Transcript

1. RethinkDB
   Tornado & Event Machine
   

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2. Ryan Paul
   RethinkDB
   Evangelist
   @segphault
   

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3. Introduction
   What is RethinkDB?
   

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4. What is RethinkDB?
   • Open source database for building
   realtime web applications
   • NoSQL database that
   stores schemaless JSON documents
   • Distributed database that is easy to
   scale
   

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5. Built for Realtime Apps
   • Subscribe to change notifications
   from database queries
   • No more polling — the database
   pushes changes to your app
   • Reduce the amount of plumbing
   needed to stream live updates
   

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6. Subscribe to change notifications
   on database queries
   Changefeeds
   

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7. r.table("users").changes()
   Changefeeds
   Track changes on the users table
   

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8. Changefeeds
   • The changes command returns a
   cursor that receives updates
   • Each update includes the new and
   old value of the modified record
   

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9. Changefeeds
   r.table("users")
   .filter({name: "Bob"}).delete()
   Changefeed output:
   {
   new_val: null,
   old_val: {
   id: '362ae837-2e29-4695-adef-4fa415138f90',
   name: 'Bob',
   ...
   }
   }
   

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10. Changefeeds
    r.table("players")
    .orderBy({index: r.desc("score")})
    .limit(3).changes()
    Track top three players by score
    Chain the changes command
    to an actual ReQL query:
    

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11. Async Frameworks
    Tornado & EventMachine
    

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12. Async Web Frameworks
    Tornado
    EventMachine
    

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13. Async Web Frameworks
    • Event-driven programming
    • Non-blocking network I/O
    • Well-suited for the realtime Web
    

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14. Async Web Frameworks
    • New in RethinkDB 2.0 Python &
    Ruby drivers
    • Download the release candidate
    today
    • Official release coming in April
    

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15. Async Web Frameworks
    • Perform queries asynchronously
    • Consume multiple changefeeds at
    the same time without blocking
    

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16. Tornado
    import rethinkdb as r
    from tornado import ioloop, gen
    r.set_loop_type("tornado")
    @gen.coroutine
    def print_changes():
    conn = yield r.connect(host="localhost", port=28015)
    feed = yield r.table("table").changes().run(conn)
    while (yield feed.fetch_next())
    change = yield feed.next()
    print(change)
    ioloop.IOLoop.current().add_callback(print_changes)
    

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17. Tornado
    import rethinkdb as r
    from tornado import ioloop, gen
    r.set_loop_type("tornado")
    @gen.coroutine
    def print_changes():
    conn = yield r.connect(host="localhost", port=28015)
    feed = yield r.table("table").changes().run(conn)
    while (yield feed.fetch_next())
    change = yield feed.next()
    print(change)
    ioloop.IOLoop.current().add_callback(print_changes)
    Configure the event loop
    

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18. Tornado
    import rethinkdb as r
    from tornado import ioloop, gen
    r.set_loop_type("tornado")
    @gen.coroutine
    def print_changes():
    conn = yield r.connect(host="localhost", port=28015)
    feed = yield r.table("table").changes().run(conn)
    while (yield feed.fetch_next())
    change = yield feed.next()
    print(change)
    ioloop.IOLoop.current().add_callback(print_changes)
    Add the coroutine decorator
    

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19. Tornado
    import rethinkdb as r
    from tornado import ioloop, gen
    r.set_loop_type("tornado")
    @gen.coroutine
    def print_changes():
    conn = yield r.connect(host="localhost", port=28015)
    feed = yield r.table("table").changes().run(conn)
    while (yield feed.fetch_next())
    change = yield feed.next()
    print(change)
    ioloop.IOLoop.current().add_callback(print_changes)
    Connect to the database
    

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20. Tornado
    import rethinkdb as r
    from tornado import ioloop, gen
    r.set_loop_type("tornado")
    @gen.coroutine
    def print_changes():
    conn = yield r.connect(host="localhost", port=28015)
    feed = yield r.table("table").changes().run(conn)
    while (yield feed.fetch_next())
    change = yield feed.next()
    print(change)
    ioloop.IOLoop.current().add_callback(print_changes)
    Perform the ReQL query
    

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21. Tornado
    import rethinkdb as r
    from tornado import ioloop, gen
    r.set_loop_type("tornado")
    @gen.coroutine
    def print_changes():
    conn = yield r.connect(host="localhost", port=28015)
    feed = yield r.table("table").changes().run(conn)
    while (yield feed.fetch_next())
    change = yield feed.next()
    print(change)
    ioloop.IOLoop.current().add_callback(print_changes)
    Iterate over changefeed changes
    

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22. Tornado
    import rethinkdb as r
    from tornado import ioloop, gen
    r.set_loop_type("tornado")
    @gen.coroutine
    def print_changes():
    conn = yield r.connect(host="localhost", port=28015)
    feed = yield r.table("table").changes().run(conn)
    while (yield feed.fetch_next())
    change = yield feed.next()
    print(change)
    ioloop.IOLoop.current().add_callback(print_changes)
    Fetch the latest change
    

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23. Tornado
    import rethinkdb as r
    from tornado import ioloop, gen
    r.set_loop_type("tornado")
    @gen.coroutine
    def print_changes():
    conn = yield r.connect(host="localhost", port=28015)
    feed = yield r.table("table").changes().run(conn)
    while (yield feed.fetch_next())
    change = yield feed.next()
    print(change)
    ioloop.IOLoop.current().add_callback(print_changes)
    Print the change to stdout
    

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24. Tornado
    import rethinkdb as r
    from tornado import ioloop, gen
    r.set_loop_type("tornado")
    @gen.coroutine
    def print_changes():
    conn = yield r.connect(host="localhost", port=28015)
    feed = yield r.table("table").changes().run(conn)
    while (yield feed.fetch_next())
    change = yield feed.next()
    print(change)
    ioloop.IOLoop.current().add_callback(print_changes)
    Run coroutine in the background
    

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25. EventMachine
    require "rethinkdb"
    include RethinkDB::Shortcuts
    conn = r.connect host: "localhost", port: 28015
    EM.run do
    r.table("table").changes.em_run(conn) do |err, change|
    puts change
    end
    end
    

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26. EventMachine
    require "rethinkdb"
    include RethinkDB::Shortcuts
    conn = r.connect host: "localhost", port: 28015
    EM.run do
    r.table("table").changes.em_run(conn) do |err, change|
    puts change
    end
    end
    Connect to the database
    

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27. EventMachine
    require "rethinkdb"
    include RethinkDB::Shortcuts
    conn = r.connect host: "localhost", port: 28015
    EM.run do
    r.table("table").changes.em_run(conn) do |err, change|
    puts change
    end
    end
    Create an EventMachine block
    

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28. EventMachine
    require "rethinkdb"
    include RethinkDB::Shortcuts
    conn = r.connect host: "localhost", port: 28015
    EM.run do
    r.table("table").changes.em_run(conn) do |err, change|
    puts change
    end
    end
    Perform the ReQL query
    

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29. EventMachine
    require "rethinkdb"
    include RethinkDB::Shortcuts
    conn = r.connect host: "localhost", port: 28015
    EM.run do
    r.table("table").changes.em_run(conn) do |err, change|
    puts change
    end
    end
    Print the change to stdout
    

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30. Building Web Apps
    Realtime Ruby app with Faye
    

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31. Faye Framework
    • Open source pub/sub framework
    for realtime messaging
    • Communication between
    frontend and backend
    • Supports Ruby and Node.js on the
    backend
    

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32. Faye Framework
    EM.run do
    ...
    App = Faye::RackAdapter.new Sinatra::Application,
    mount: "/faye"
    conn = r.connect host: "localhost", port: 28015
    r.table("todo").changes.em_run(conn) do |err, change|
    App.get_client.publish("/todo/update", change)
    end
    ...
    end
    Server-side Ruby code
    

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33. Faye Framework
    EM.run do
    ...
    App = Faye::RackAdapter.new Sinatra::Application,
    mount: "/faye"
    conn = r.connect host: "localhost", port: 28015
    r.table("todo").changes.em_run(conn) do |err, change|
    App.get_client.publish("/todo/update", change)
    end
    ...
    end
    Initialize Faye and bind URL route
    

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34. Faye Framework
    EM.run do
    ...
    App = Faye::RackAdapter.new Sinatra::Application,
    mount: "/faye"
    conn = r.connect host: "localhost", port: 28015
    r.table("todo").changes.em_run(conn) do |err, change|
    App.get_client.publish("/todo/update", change)
    end
    ...
    end
    Connect to the database
    

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35. Faye Framework
    EM.run do
    ...
    App = Faye::RackAdapter.new Sinatra::Application,
    mount: "/faye"
    conn = r.connect host: "localhost", port: 28015
    r.table("todo").changes.em_run(conn) do |err, change|
    App.get_client.publish("/todo/update", change)
    end
    ...
    end
    Perform the ReQL query
    

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36. Faye Framework
    EM.run do
    ...
    App = Faye::RackAdapter.new Sinatra::Application,
    mount: "/faye"
    conn = r.connect host: "localhost", port: 28015
    r.table("todo").changes.em_run(conn) do |err, change|
    App.get_client.publish("/todo/update", change)
    end
    ...
    end
    Publish the update to a channel
    

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37. Faye Framework
    faye.subscribe("/todo/update", function(data) {
    console.log(data);
    });
    Client-side JavaScript code
    

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38. DEMO
    

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