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?
7. She’s called Eleanor
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
23. Client → Server Server → DB Computation Computation Internet Computing
24. “Traditional” Approach
26. Server
27. Request
30. FULL
31. Event-driven Approach
32. Request Place- holder
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?
46. What is the event loop?
48. Multi-tasking, one thing at a time.
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
68. Remote operation
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