Increasingly we want to do more with the web and Internet applications we build. We have more features, more data, more users, more devices and all of it needs to be in real-time. With all of these demands how can we keep up? The answer is choosing a language and a platform that are optimized for the kind of architecture Internet and web applications really have. The traditional approach prioritises computation, assigning server resources before they are actually needed. JavaScript and Node.js both take an event driven approach only assigning resources to events as they happen. This allows us to make dramatic gains in performance and resource utilization while still having an environment which is fun and easy to program.

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

2. Me

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

6. Internet?

9. She’s called Eleanor

15. More features
More users
More devices
More data

16. Cost
Stuff

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

18. Internet Applications

19. How about search?

20. Browser
Server
Spidering... The Web

21. Would take forever!

22. Browser
Front-end
Server
Database

23. Client → Server
Computation

24. Client → Server Server → DB
Computation Computation

25. “Traditional” Approach

27. Server

28. Request

31. U L L
F

32. Event-driven Approach

33. Place-
holder

35. Shared
Work
Resources

36. Welcome to Node.js

37. 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

38. $Enki:~ $ node

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

40. > 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:~ $

41. 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)

42. 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/');

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

44. 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

45. 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

46. 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

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

49. What is the event
loop?

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

54. 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/');

55. 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'

56. 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

57. 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

58. 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.

59. 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

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/');
Step 3.
'request' is called. Since
listeners: server.request -> function
Call function

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 3.
Loop!
(go to Step 2.)

62. Breaking the event
loop

64. 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');

65. Why non-blocking
matters

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

67. What are we
waiting for?

69. "Blocking" is as bad
as stopping

70. Event Loop vs.
Threads

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

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

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

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

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

76. Thanks!
Questions?
Tom Hughes-Croucher
@sh1mmer