node.js is an evented server-side Javascript framework powered by the Google V8 Javascript engine. It is a platform ideal for creating highly scalable web applications. It has the same simplicity of frameworks such as Sinatra, but is designed to be more peformant from the ground up. This performance is achieved by making all network I/O non blocking and all file I/O asynchronous. We will go over how that impacts the development experience, and walk through a simple web application. Javascript is foundational to this type of I/O because it is already evented by design. We will also take a brief look a similar evented frameworks such as ruby`s EventMachine.

1. PLAYING WITH FIRE
(ROCKET FUEL ACTUALLY)
An introduction to node.js

2. Mike Hagedorn Anthony Broussard
@mwhagedorn @quantumpotato
codemav.com/mwhagedorn codemav.com/quantumpotato
mike@silverchairsolutions.com anthony@chaione.com

3. IN THE BEGINNING...
Server-side Javascript

4. IN THE BEGINNING...
Server-side Javascript
(it sucked)

5. SERVER-SIDE JAVASCRIPT
•Netscape Livewire(1996)
•Rhino(1997)
•Several others since(like 50)

6. Y SO BAD?
•Slow Engines
•Javascript’s Perception (until recently)
•Much better alternatives

7. Y IZ BETTR NAO?
Lots of Competition
•SpiderMonkey
•JavascriptCore
•Chakra
Javascript is cool now!

9. WHAT IS NODE.JS?
•Created By Ryan Dahl
•Google’s V8 Engine (No DOM)
•Uses Nonblocking I/O
•Single Threaded
•A New Way To Build Scalable Network Platforms

10. WHY SHOULD YOU CARE?
•Its Fast
> summary(node1$ttime)
Min. 1st Qu. Median Mean 3rd Qu. Max.
0.0000 0.0000 1.0000 0.7437 1.0000 106.0000
> summary(thin1$ttime)
Min. 1st Qu. Median Mean 3rd Qu. Max.
0.000 1.000 1.000 1.122 1.000 74.000
> summary(narwhal1$ttime)
Min. 1st Qu. Median Mean 3rd Qu. Max.
15.00 22.00 23.00 23.74 24.00 88.00
> summary(v8cgi1$ttime)
Min. 1st Qu. Median Mean 3rd Qu. Max.
12.00 13.00 13.00 14.49 18.00 39.00

11. WHY SHOULD YOU CARE?
•It can handle LOTS of concurrent transactions

12. WHY SHOULD YOU CARE?
• Makes near real time things easy
• Its small
• Its Javascript
•(Second most used language on Github)

13. WHO’S USING IT
Others: http://doiop.com/rocket-node

14. HELLO WORLD
server.js

15. HELLO WORLD
server.js
setTimeout(function(){
console.log(“world”)
},2000);
console.log(“hello”);

16. HELLO WORLD
server.js
setTimeout(function(){
console.log(“world”)
},2000);
console.log(“hello”);
$ node server.js
hello
world

17. HELLO WORLD
server.js
setTimeout(function(){
console.log(“world”)
},2000);
console.log(“hello”);
print(“hello”);
sleep(2000);
print(“world”);
$ node server.js
hello
world

18. NON-BLOCKING I/O
(asynchronous is the new black)

19. BLOCKING I/O
var a = db.query('SELECT A');
console.log('result a:', a);
var b = db.query('SELECT B');
console.log('result b:', b);
Time = SUM(A, B)

20. NON-BLOCKING I/O
db.query('SELECT A', function(result) {
console.log('result a:', result);
});
db.query('SELECT B', function(result) {
console.log('result b:', result);
});
Time = MAX(A, B)

21. SINGLE THREADED!
You have to use callbacks!
db.query('SELECT A', function(result) {
object.mySlowCall(result, function(){
console.log(“my result”);
})
});

22. WHY ISN’T EVERYONE USING
NON-BLOCKING I/O?
There are cultural and infrastructural
reasons

23. CULTURAL BIAS
We’re taught I/O with this:
puts(“Enter your name:”)
var name = gets()
We’re taught to demand input and do
nothing until we have it.

24. CULTURAL BIAS
This code:
puts(“Enter your name:”)
var name = gets(function(name){
puts(“Name: “)+name);
})
is rejected as TOO COMPLICATED

25. MISSING INFRASTRUCTURE
So why isn’t everyone using event loops?
Single threaded event loops require I/O to be non blocking
Most libraries are not.

26. OTHER APPROACHES?
•Twisted
•EventMachine
•Others
•Have lots of blocking libs to contend with
•From the start Node has never provided a blocking API
•Its a clean slate
•These approaches can be hard to use

27. JAVASCRIPT...
•Has had event loops from the beginning
•Anonymous functions, closures
•Single threaded
•The culture of Javascript embraces evented
programming

28. GREAT FOR
•Single Page Apps
•Realtime updates
•Processors/Crawlers
•Process Monitoring
•File Uploading

29. INSTALLING
OSX
$ brew install node
Linux
$ git clone ....
$ configure
$ make
Windows
Not Yet (version 0.6)

30. INSTALLING NPM
•Node Package Manager
•Similar to RubyGems, Python easy_install
$ curl http://npmjs.org/install.sh | sh

31. COMMON JS MODULES
hello.js
exports.world = function(){
return “Hello World”;
}
main.js
var hello = require(‘./hello’);
var sys = require(‘sys’);
sys.puts(hello.world());
$ node main.js #Hello World

32. EVENTS
{EventEmitter} = require ‘events’
emitter = new EventEmitter
emitter.on ‘foo’, -> console.log ‘bar’
emitter.emitusual new_monster event. And check out how much nicer our
emitting the ‘foo’
dependency graph has become!
http://pragprog.com/magazines/2011-08/content
Imagine No Dependencies
A lot of Node developers will tell you that attaching things to global rather
than exports is a no-no. And if you’re packaging your code as a library, or trying
to make your code reusable, then they’re right. But if you’re developing a
standalone application, then go ahead and let yourself declare a few globals.

33. QUEUEING AN EVENT
function longFunction(){};
process.nextTick(longFunction);
Call longfunction on next time through event loop

34. EMITTING AN EVENT
var events = require('events');
var eventEmitter = new events.EventEmitter();
eventEmitter.on('someOccurence', function(message){
console.log(message);
});
eventEmitter.emit('someOccurence', 'Something happened!');

35. MANAGING ASYNCHRONCITY
A B C
use async!

36. MANAGING ASYNCHRONCITY
A B C
var operation = function(a_data, b_data, callback){
async.series([
function(as_callback),
function(as_callback),
function(err,results){ //[resulta, resultb] }
]);
}

37. MANAGING ASYNCHRONCITY
A
C
B
var operation = function(a_data, b_data, callback){
async.parallel([
function(as_callback),
function(as_callback),
function(err,results){ //[resulta, resultb] }
]);
}

38. EXPRESS WEB FRAMEWORK
var app = express.createServer();
app.get('/', function(req, res){
res.send('Hello World');
});
app.listen(3000);

39. COFFEESCRIPT
•“Little language that compiles to javascript”
•“It’s just javascript”
• More ruby-like

40. COFFEESCRIPT
•“Little language that compiles to javascript”
•“It’s just javascript”
• More ruby-like
square = (x) -> x * x

41. COFFEESCRIPT
•“Little language that compiles to javascript”
•“It’s just javascript”
• More ruby-like
square = (x) -> x * x
square = function(x){
return x * x;
}

42. DEMO

43. QUESTIONS?
http://spkr8.com/t/8178
Mike Hagedorn Anthony Broussard
@mwhagedorn @quantumpotato
mike@silverchairsolutions.com anthony@chaione.com