Node.js and JavaScript are well-suited for Internet applications because Node.js uses an event-driven, non-blocking I/O model that makes it lightweight and efficient, capable of supporting many more concurrent connections than traditional server-side models like Apache. This event loop system allows Node.js to handle multiple requests simultaneously without blocking any specific request. It also minimizes memory usage so more requests can be served from fewer servers.

1. A language for the
Internet
Why JavaScript and Node.js is right for
Internet Applications
Tom Hughes-Croucher
@sh1mmer

2. Me
(@sh1mmer)

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

6. A brief aside.
A small lecture on
biology

7. The common tree shrew

8. Diana Monkey

11. Back to your feature
presentation.

12. Internet?

15. She’s called Eleanor

21. More features
More users
More devices
More data

22. Cost
Stuff

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

24. Internet Applications

25. How about search?

26. Browser
Server
Spidering... The Web

27. Would take forever!

28. Browser
Front-end
Server
Computation
Database

29. Computational Computing
Client → Server
Computation

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

31. “Traditional” Approach

33. Server

34. Request

37. U L L
F

38. Event-driven Approach

39. Place-
holder

41. Shared
Work
Resources

42. Welcome to Node.js

43. 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

44. $Enki:~ $ node

45. $Enki:~ $ node
>3>2>1
false
> true == 1
true
> true === 1
false

46. > console.log('Hello World');
Hello World
> .help
.clear Break, and also clear the local context.
.exit Exit the prompt
.help Show repl options
> .clear
Clearing context...
> .exit
Enki:~ $

47. Enki:~ $ node
> var foo = "bar";
> foo;
'bar'
> .clear
Clearing context...
> foo
ReferenceError: foo is not defined
at [object Context]:1:1
at Interface.<anonymous> (repl:98:19)
at Interface.emit (events:27:15)
at Interface._ttyWrite (readline:295:12)
at Interface.write (readline:132:30)
at Stream.<anonymous> (repl:79:9)
at Stream.emit (events:27:15)
at IOWatcher.callback (net:489:16)

48. var http = require('http');
http.createServer(function (req, res) {
res.writeHead(200, {'Content-Type': 'text/plain'});
res.end('Hello Worldn');
}).listen(8124, "127.0.0.1");
console.log('Server running at http://127.0.0.1:8124/');

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

50. 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

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

52. 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

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

55. What is the event
loop?

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

60. var http = require('http');
server = http.createServer();
server.on('request', function (req, res) {
res.writeHead(200, {'Content-Type': 'text/plain'});
res.end('Hello Worldn');
});
server.listen(8124, "127.0.0.1");
console.log('Server running at http://127.0.0.1:8124/');

61. var http = require('http');
server = http.createServer();
server.on('request', function (req, res) {
res.writeHead(200, {'Content-Type': 'text/plain'});
res.end('Hello Worldn');
});
server.listen(8124, "127.0.0.1");
console.log('Server running at http://127.0.0.1:8124/');
Step 1.
Evaluate 'Main'

62. var http = require('http');
server = http.createServer();
server.on('request', function (req, res) {
res.writeHead(200, {'Content-Type': 'text/plain'});
res.end('Hello Worldn');
});
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

63. var http = require('http');
server = http.createServer();
*
server.on('request', function (req, res) {
res.writeHead(200, {'Content-Type': 'text/plain'});
res.end('Hello Worldn');
});
server.listen(8124, "127.0.0.1");
console.log('Server running at http://127.0.0.1:8124/');
Step 2.
Event Loop

64. var http = require('http');
server = http.createServer();
*
server.on('request', function (req, res) {
res.writeHead(200, {'Content-Type': 'text/plain'});
res.end('Hello Worldn');
});
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.

65. var http = require('http');
server = http.createServer();
server.on('request', function (req, res) {
res.writeHead(200, {'Content-Type': 'text/plain'});
res.end('Hello Worldn');
});
server.listen(8124, "127.0.0.1");
console.log('Server running at http://127.0.0.1:8124/');
Step 3.
Event Calls

66. var http = require('http');
server = http.createServer();
server.on('request', function (req, res) {
res.writeHead(200, {'Content-Type': 'text/plain'});
res.end('Hello Worldn');
});
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

67. var http = require('http');
server = http.createServer();
server.on('request', function (req, res) {
res.writeHead(200, {'Content-Type': 'text/plain'});
res.end('Hello Worldn');
});
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.)

68. Breaking the event
loop

70. EE = require('events').EventEmitter;
ee = new EE();
die = false;
ee.on('die', function() {
die = true;
});
setTimeout(function() {
ee.emit('die');
}, 100);
while(!die) {
}
console.log('done');

71. Why non-blocking
matters

72. var result =
db.query("select * from T");
// use result

73. What are we
waiting for?

75. "Blocking" is as bad
as stopping

76. Event Loop vs.
Threads

77. PHP
8mb
8gb ram
8000/8 = 1000
~1000 users per
machine

78. Node.js
TCP = 2kb
HTTP = 6kb
8gb ram
8000/0.006 = 1.3m
1.3m/2 ~ 650k users

79. Apache vs NGINX
concurrency × reqs/sec
http://blog.webfaction.com/a-little-holiday-present

80. Apache vs NGINX
concurrency × memory
http://blog.webfaction.com/a-little-holiday-present

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

82. Thanks!

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