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Node.js - A practical introduction (v2)

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Node.js - A practical introduction (v2)

  1. 1. A practical introduction Felix Geisendörfer Munich Node.js User Group 01.12.2011 (v2)
  2. 2. @felixge Twitter / GitHub / IRC Felix Geisendörfer (Berlin, Germany)
  3. 3. Node.js in Munich?
  4. 4. Used node before?
  5. 5. Node in production?
  6. 6. History
  7. 7. Feb 16, 2009 Ryan Dahl starts the node project (first commit)
  8. 8. ~June, 2009 Discovered node.js (v0.0.6)
  9. 9. transloadit.com
  10. 10. Core Contributor & Module Author node-mysql node-formidable + 30 other modules
  11. 11. Sep 29, 2009 Isaac Schlueter starts the npm package manager (first commit)
  12. 12. Nov 7, 2009 Ryan’s talk at JSConf.EU gets people excited about node
  13. 13. Today
  14. 14. #1 Most watched repository on GitHub
  15. 15. ...
  16. 16. 0.6.3 was released 6 days ago (Nov 25)
  17. 17. Companies using node • LinkedIn (Mobile Web App) • Ebay (Data retrieval gateway) • GitHub (for Downloads) • Palm/HP (in WebOS) • Yahoo! Mail • Dow Jones & Company (for WJS social site) • Rackspace (Cloudkick monitoring) • Voxxer (Push to Talk mobile app)
  18. 18. Installing $ git clone git://github.com/joyent/node.git $ cd node $ git checkout v0.6.0 $ ./configure $ sudo make install (windows users: download node.exe)
  19. 19. Hello World hello.js console.log('Hello World');
  20. 20. Hello World hello.js console.log('Hello World'); $
  21. 21. Hello World hello.js console.log('Hello World'); $ node
  22. 22. Hello World hello.js console.log('Hello World'); $ node hello.js
  23. 23. Hello World hello.js console.log('Hello World'); $ node hello.js Hello World
  24. 24. Hello World (REPL)
  25. 25. Hello World (REPL) $
  26. 26. Hello World (REPL) $ node
  27. 27. Hello World (REPL) $ node >
  28. 28. Hello World (REPL) $ node > console.log('Hello World')
  29. 29. Hello World (REPL) $ node > console.log('Hello World') Hello World
  30. 30. Http Server http_server.js var http = require('http'); var server = http.createServer(function(req, res) { res.end('Hi, how are you?'); }); server.listen(8080);
  31. 31. Http Server http_server.js var http = require('http'); var server = http.createServer(function(req, res) { res.end('Hi, how are you?'); }); server.listen(8080); $ node http_server.js
  32. 32. Http Server http_server.js var http = require('http'); var server = http.createServer(function(req, res) { res.end('Hi, how are you?'); }); server.listen(8080); $ node http_server.js $ curl localhost:8080 Hi, how are you?
  33. 33. “Come on, server side JS has been around since 1996”
  34. 34. What is so special about node?
  35. 35. Speed
  36. 36. Speed • Node can do ~6000 http requests / sec per CPU core (hello world, 1kb response,) • It is no problem to handle thousands of concurrent connections which are moderately active
  37. 37. V8 JavaScript Engine
  38. 38. V8 JavaScript Engine • Developed by Google in Aarhus, Denmark for Google Chrome • Translates JavaScript in Assembly Code • Crankshaft JIT (enabled in 0.6.0 by default)
  39. 39. V8 JavaScript Engine • You can expect to be within ~10x of C performance usually • Certain code can run within 2-3x of C • Getting faster all the time
  40. 40. Non-Blocking I/O
  41. 41. Blocking I/O read_file_sync.js var fs = require('fs'); var one = fs.readFileSync('one.txt', 'utf-8'); console.log('Read file one'); var two = fs.readFileSync('two.txt', 'utf-8'); console.log('Read file two');
  42. 42. Blocking I/O read_file_sync.js var fs = require('fs'); var one = fs.readFileSync('one.txt', 'utf-8'); console.log('Read file one'); var two = fs.readFileSync('two.txt', 'utf-8'); console.log('Read file two'); $ node read_file_sync.js
  43. 43. Blocking I/O read_file_sync.js var fs = require('fs'); var one = fs.readFileSync('one.txt', 'utf-8'); console.log('Read file one'); var two = fs.readFileSync('two.txt', 'utf-8'); console.log('Read file two'); $ node read_file_sync.js Read file one
  44. 44. Blocking I/O read_file_sync.js var fs = require('fs'); var one = fs.readFileSync('one.txt', 'utf-8'); console.log('Read file one'); var two = fs.readFileSync('two.txt', 'utf-8'); console.log('Read file two'); $ node read_file_sync.js Read file one Read file two
  45. 45. Non-Blocking I/O read_file_async.js var fs = require('fs'); fs.readFile('one.txt', 'utf-8', function(err, data) { console.log('Read file one'); }); fs.readFile('two.txt', 'utf-8', function(err, data) { console.log('Read file two'); });
  46. 46. Non-Blocking I/O read_file_async.js var fs = require('fs'); fs.readFile('one.txt', 'utf-8', function(err, data) { console.log('Read file one'); }); fs.readFile('two.txt', 'utf-8', function(err, data) { console.log('Read file two'); }); $ node read_file_async.js
  47. 47. Non-Blocking I/O read_file_async.js var fs = require('fs'); fs.readFile('one.txt', 'utf-8', function(err, data) { console.log('Read file one'); }); fs.readFile('two.txt', 'utf-8', function(err, data) { console.log('Read file two'); }); $ node read_file_async.js Read file two
  48. 48. Non-Blocking I/O read_file_async.js var fs = require('fs'); fs.readFile('one.txt', 'utf-8', function(err, data) { console.log('Read file one'); }); fs.readFile('two.txt', 'utf-8', function(err, data) { console.log('Read file two'); }); $ node read_file_async.js Read file two Read file one
  49. 49. Blocking I/O Read one.txt (20ms) Read two.txt (10ms) Total duration (30ms)
  50. 50. Non-Blocking I/O Read one.txt (20ms) Read two.txt (10ms) Total duration (20ms)
  51. 51. Non-Blocking I/O • Close to ideal for high concurrency / high throughput, single execution stack • Forces you to write more efficient code by parallelizing your I/O • Feels pretty much like AJAX in the browser
  52. 52. WebSockets (Push)
  53. 53. WebSockets • Persistent connection between browser/server • Very hard / awkward to do on traditional stacks • Hard to scale on traditional stacks
  54. 54. Socket.IO (community module) • WebSocket • Adobe® Flash® Socket • AJAX long polling • AJAX multipart streaming • Forever Iframe • JSONP Polling Chooses most capable transport at runtime!
  55. 55. Streams
  56. 56. “Streams are to time as arrays are to space.” -- Jed Schmidt @ JSConf.eu 2010
  57. 57. Streams in node.js • Readable • Writable • Both
  58. 58. Streams var http = require('http'); var server = http.createServer(function(req, res) { req.on('data', console.log); }); server.listen(8080);
  59. 59. Streams var http = require('http'); var server = http.createServer(function(req, res) { req.on('data', console.log); }); server.listen(8080); $ node stream.js & $ curl -F file=@stream.js localhost:8080 ------------------------------41e92562223e Content-Disposition: form-data; name="file"; filename Content-Type: application/octet-stream var http = require('http'); var server = http.createServer(function(req, res) {
  60. 60. Streams var http = require('http'); var spawn = require('child_process').spawn; http.createServer(function(req, res) { var params = req.url.split('/'); var args = [params[1], '-resize', params[2], '-']; var convert = spawn('convert', args); convert.stdout.pipe(res); }).listen(8080);
  61. 61. On Github felixge/node-convert-example
  62. 62. NPM package manager
  63. 63. NPM • Puts dependencies in the right place, then gets out of your way • No modification of a global load path (require.paths is gone in 0.6.x) • 5369+ Modules in npm, > 10 new modules / day
  64. 64. So what is node good for?
  65. 65. Use cases • WebSockets/Push applications • Proxying data streams • Backend for single page apps
  66. 66. Use cases • Spawning other programs (processes) to do work / IPC • Parallelizing I/O
  67. 67. So what is node not good for?
  68. 68. Anti-Use cases • Hard Realtime Systems • Number crunching / huge in-memory datasets • (CRUD apps)
  69. 69. Join the Community • Mailing list (nodejs, nodejs-dev) • IRC (#node.js) - 700+ User online
  70. 70. Thank you!
  71. 71. Questions? @felixge
  72. 72. Thank you!
  73. 73. Bonus Slide
  74. 74. What’s next? • Domains • Improved Stream API

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  • Mention difference between node / other platforms where you’re implicitly embedded inside a webserver\n
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  • If that is not fast enough for what you’re doing, use C\n
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  • Now you may say:\n- This is terrible\n- I have to write 7 lines instead of 5\n- And it’s in the wrong order\n\n
  • Now you may say:\n- This is terrible\n- I have to write 7 lines instead of 5\n- And it’s in the wrong order\n\n
  • Now you may say:\n- This is terrible\n- I have to write 7 lines instead of 5\n- And it’s in the wrong order\n\n
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  • A keen observer may note that the same is achievable with threads\n* But how many of you think threading is easier than making an AJAX call\n* Threads require significant more resources than the non-blocking I/O node is doing\n
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