Node.js - Dibi 2012

Transcript

1. A language for the Internet Why JavaScript and Node.js is

   right for Internet Applications Tom Hughes-Croucher @sh1mmer

2. Me (@sh1mmer)

3. Scalable Server-Side Code with JavaScript Tom Hughes-Croucher Node Up and

   Running

4. Internet?

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6. None

7. She’s called Eleanor

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13. More features More users More devices More data

14. Stuff Cost

15. How do we cope with the increase in demand?

16. Internet Applications

17. How about search?

18. Browser Spidering Server Web Sites

19. Would take forever!

20. Browser Front-end Server Database Computation

21. Client → Server Computation Batch Computing

22. None

23. Client → Server Server → DB Computation Computation Internet Computing

24. “Traditional” Approach

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26. Server

27. Request

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30. FULL

31. Event-driven Approach

32. Request Place- holder

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34. Shared Work Resources

35. Welcome to Node.js

36. Node.js? • Server Side JavaScript runtime • Built on top

    of V8 JavaScript engine from Google Chrome • Non-blocking I/O APIs • Easy to extend APIs and modules

37. $Enki:~ $ node

38. $Enki:~ $ node > 3 > 2 > 1 false

    > true == 1 true > true === 1 false

39. var http = require('http'); http.createServer(function (req, res) { res.writeHead(200, {'Content-Type':

    'text/plain'}); res.end('Hello World\n'); }).listen(8124, "127.0.0.1"); console.log('Server running at http://127.0.0.1:8124/');

40. var http = require('http'); //include the http library

41. http.createServer(function (req, res) { }).listen(8124, "127.0.0.1"); //create an http server

    //when ‘stuff’ happens call this anonymous function //listen on port 8124 of the IP 127.0.0.1

42. http.createServer(function (req, res) { res.writeHead(200, {'Content-Type': 'text/plain'}); res.end('Hello World\n'); })

    //when ‘stuff’ happens my function fires //I get a request object and a response object //I write to the response object header //HTTP status 200 and content-type ‘text/plain’ //close the response with the body: //Hello World

43. console.log('Server running at http://127.0.0.1:8124/'); //write Server is running at http://127.0.0.1:8124/

    //to the console

44. Why is Node.js suited to Internet Apps?

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46. What is the event loop?

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48. Multi-tasking, one thing at a time.

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51. var http = require('http'); server = http.createServer(); server.on('request', function (req,

    res) { res.writeHead(200, {'Content-Type': 'text/plain'}); res.end('Hello World\n'); }); server.listen(8124, "127.0.0.1"); console.log('Server running at http://127.0.0.1:8124/');

52. var http = require('http'); server = http.createServer(); server.on('request', function (req,

    res) { res.writeHead(200, {'Content-Type': 'text/plain'}); res.end('Hello World\n'); }); server.listen(8124, "127.0.0.1"); console.log('Server running at http://127.0.0.1:8124/'); Step 1. Evaluate 'Main'

53. var http = require('http'); server = http.createServer(); server.on('request', function (req,

    res) { res.writeHead(200, {'Content-Type': 'text/plain'}); res.end('Hello World\n'); }); server.listen(8124, "127.0.0.1"); console.log('Server running at http://127.0.0.1:8124/'); Step 1. variables: http -> http module server -> http server listeners: server.request -> function

54. var http = require('http'); server = http.createServer(); server.on('request', function (req,

    res) { res.writeHead(200, {'Content-Type': 'text/plain'}); res.end('Hello World\n'); }); server.listen(8124, "127.0.0.1"); console.log('Server running at http://127.0.0.1:8124/'); Step 2. Event Loop *

55. var http = require('http'); server = http.createServer(); server.on('request', function (req,

    res) { res.writeHead(200, {'Content-Type': 'text/plain'}); res.end('Hello World\n'); }); server.listen(8124, "127.0.0.1"); console.log('Server running at http://127.0.0.1:8124/'); Step 2. Do we have active listeners? listeners: server.request -> function Yes! Wait for listeners. *

56. var http = require('http'); server = http.createServer(); server.on('request', function (req,

    res) { res.writeHead(200, {'Content-Type': 'text/plain'}); res.end('Hello World\n'); }); server.listen(8124, "127.0.0.1"); console.log('Server running at http://127.0.0.1:8124/'); Step 3. Event Calls

57. var http = require('http'); server = http.createServer(); server.on('request', function (req,

    res) { res.writeHead(200, {'Content-Type': 'text/plain'}); res.end('Hello World\n'); }); server.listen(8124, "127.0.0.1"); console.log('Server running at http://127.0.0.1:8124/'); Step 3. 'request' is called. Since listeners: server.request -> function Call function

58. var http = require('http'); server = http.createServer(); server.on('request', function (req,

    res) { res.writeHead(200, {'Content-Type': 'text/plain'}); res.end('Hello World\n'); }); server.listen(8124, "127.0.0.1"); console.log('Server running at http://127.0.0.1:8124/'); Step 3. Loop! (go to Step 2.)

59. Why non-blocking matters

60. Event Loop vs. Threads

61. //node.js style JavaScript query = mysql.query('SELECT * FROM data'); query.on(‘result’,

    function(result) { for(var i=0;i<length;i++) { var row = result.rows[i]; //do something with the row } });

62. //threaded style JavaScript result = mysql.query('SELECT * FROM data'); for(var

    i=0;i<length;i++) { var row = result.rows[i]; //do something with the row }

63. var x = "I am a string" ~1ns Running 1

    instruction 2ns Data from l1 cpu cache 5ns Data from l2 cpu cache 80ns Data from ram

64. Server mySQL query result

65. result = mysql.query('SELECT * FROM data'); ~100ms Time to run

    a query in database 50ms Time to roundtrip query over the network

66. Local variable

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68. Remote operation

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70. Cat 100 Blue Whales

71. Blocking is as bad as stopping

72. Threading wastes memory for a long time because of programming

    style

73. 2mb PHP 8gb ram 8000/2 = 4000 ~4000 users per

    machine

74. 8gb ram 8000/0.006 = 1.3m 1.3m/2 ~ 650k users Node.js

    TCP = 2kb HTTP = 6kb

75. Node.js is designed for communication, just like your applications

76. Demo

77. Thanks!

78. Follow me @sh1mmer Tom Hughes-Croucher @sh1mmer