Building Asynchronous Communication Layer

At Hulu, we built an asynchronous automation framework using XMPP, Ruby, and JavaScript called Bender. We use it with Roku, Playstation 3, Wii, Android, and iOS devices. This talk is a tour of some of the key technologies we chose and why we are using them.

Transcript

1. Building Asynchronous Communication Layer Using XMPP, Ruby, and JavaScript Andrew Carter and Steve Jang 1 Tuesday, April 24, 12
2. 2007 2 Tuesday, April 24, 12
3. hulu.com 3 Tuesday, April 24, 12
4. To help people find and enjoy the world’s premium content when, where, and how they want it. 4 Tuesday, April 24, 12
5. Web Only Safari, Firefox, Internet Explorer 5 Tuesday, April 24, 12
6. Built with Ruby on Rails 6 Tuesday, April 24, 12
7. People liked Hulu 7 Tuesday, April 24, 12
8. but ... 8 Tuesday, April 24, 12
9. People like to watch TV on TV 9 Tuesday, April 24, 12
10. Today 10 Tuesday, April 24, 12
11. 11 Tuesday, April 24, 12
12. 12 Tuesday, April 24, 12
13. Hulu on Mobile and in Living Room 13 Tuesday, April 24, 12
14. Hulu Japan 14 Tuesday, April 24, 12
15. Over 60 Devices 15 17 Manufacturers Tuesday, April 24, 12
16. Devices create new problems 16 Tuesday, April 24, 12
17. •Multiple platforms (JavaScript, native UI) •Custom tools for each platform •Streaming video •Network conditions Why devices can be difficult 17 Tuesday, April 24, 12
18. Testing Video Streaming 18 •Sensitive to network conditions and hardware •Achieving repeatability •Playback engines different for each platform •Time consuming Tuesday, April 24, 12
19. Help! 19 We need a new toolchain Tuesday, April 24, 12
20. Requirements 20 •Adaptable to multi-platform •Works via HTTP •Scriptable •Measures Quality of Service Tuesday, April 24, 12
21. Bender 21 Tuesday, April 24, 12
22. Bender Architecture 22 Tuesday, April 24, 12
23. Bender Architecture 23 Tuesday, April 24, 12
24. XMPP 24 ejabberd and BOSH Tuesday, April 24, 12
25. XMPP 25 Tuesday, April 24, 12
26. XMPP 26 Tuesday, April 24, 12
27. •Open TCP connection •Polling over HTTP •Long Polling Bi-directional Messaging Solutions 27 Tuesday, April 24, 12
28. •Cramp/EventMachine + REDIS •Nginx + http_push_mod •Cometd Long Polling Options 28 Tuesday, April 24, 12
29. •Asynchronous Message •Authentication via SASL •Encryption via TLS •Presence and Roster Management XMPP 29 Tuesday, April 24, 12
30. •Minimal Latency •Works with constrained clients •HTTP 1.0, no cookies, no headers •No chunked transfer coding BOSH (XMPP over HTTP) 30 Tuesday, April 24, 12
31. •Reference Jabber server •Runs jabber.org public service •Scale to 5000-10,000 concurrent clients •Erlang •Installation •Via chef recipe •Nginx to proxy port 80 to port 5280 ejabberd 31 Tuesday, April 24, 12
32. XMPP4R XMPP + Ruby 32 Tuesday, April 24, 12
33. XMPP4R 33 Tuesday, April 24, 12
34. XMPP4R 34 Tuesday, April 24, 12
35. •Ruby implementation of XMPP client •Asynchronous API •Threaded library •Uses REXML •Alternatives •Blather (EventMachine + Nokogiri) •Net::XMPP •Jabber4R XMPP4R 35 Tuesday, April 24, 12
36. Strophe.js XMPP + JavaScript 36 Tuesday, April 24, 12
37. Strophe.js 37 Tuesday, April 24, 12
38. Strophe.js 38 Tuesday, April 24, 12
39. •JavaScript implementation of BOSH •Uses XMLHTTPRequest •XML builder API •Plug-in support : Strophe.addConnectionPlugin •Alternatives •JSJaC •Xmpp4js •http://xmpp.org/xmpp-software Strophe.js 39 Tuesday, April 24, 12
40. Strophe.js Plugin 40 Strophe.addConnectionPlugin('htv', { init: function (connection) { /* Platform-specific code */ }, register: function(address, password, successCb) { this.registerSuccessCb = successCb; this.connection._addSysHandler(successCb, Strophe.NS.REGISTER, null, "result", regId); this.connection.send( $iq({ type: "set”, to: domain, id: regId }) .c("query", { xmlns: Strophe.NS.REGISTER }) .c("username", {}).t(node).up() .c("password", {}).t(password).up() .c("username", {}).t(account).up() .c("password", {}).t(password) ); } }); Tuesday, April 24, 12
41. Bender Ruby scripting layer 41 Tuesday, April 24, 12
42. Bender 42 Tuesday, April 24, 12
43. Bender 43 Tuesday, April 24, 12
44. •Ruby API to control remote devices •Simple DSL •Device agnostic command/response protocol •Synchronous API via Asynchronous transport •Delivered as a Ruby gem •Certification Test Suite •Runs on Ruby 1.9.3 Bender 44 Tuesday, April 24, 12
45. def test_basic_playback_start @device.session.start @device.ensure_logged_in(cred) @device.playback_start( :content_id => “192834”) @device.wait_for(:playback_progress) @device.playback_stop @device.session.end # (omitted) # assertions wrt @device.session end Bender Script 45 Tuesday, April 24, 12
46. def send_command(cmd) resp = nil @resp_mutex.synchronize do @transport.transmit(cmd.serialize_to_json) @resp_cond.wait(@resp_mutex, cmd.timeout) resp = @received.delete(cmd.response_id) if resp.nil? raise RequestTimeOut.new(“timed out!”) end end return resp end Ruby Threading 46 Tuesday, April 24, 12
47. Lessons 47 Tuesday, April 24, 12
48. Use off-the-shelf components XMPP minitest Ruby 48 Tuesday, April 24, 12
49. XMPP as lightweight middleware 49 Tuesday, April 24, 12
50. Efficiency gains from automation 50 Tuesday, April 24, 12
51. Tests can be documentation 51 Tuesday, April 24, 12
52. Strophe is difficult without a DOM 52 Tuesday, April 24, 12
53. REXML with Unicode Jabber uses streams of segments as part of document which default to ASCII not UTF-8 53 Tuesday, April 24, 12
54. •Device provisioning •Automated grids •Non-testing applications Other Possibilities 54 Tuesday, April 24, 12
55. •http://xmpp.org •http://strophe.im •http://professionalxmpp.com •http://github.com/hulu Further Information 55 Tuesday, April 24, 12
56. Questions? 56 hulu.com/jobs Seattle — Santa Monica — Beijing Tuesday, April 24, 12