1. node.js
A quick tour
by Felix Geisendörfer
Donnerstag, 4. März 2010 1

2. Who is talking?
• node.js hacker
• Cofounder of Debuggable
• CakePHP core alumnus
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3. Why Node?
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4. Why?
Node's goal is to provide an easy
way to build scalable network
programs.
-- nodejs.org
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5. How?
Keep slow operations from
blocking other operations.
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6. Traditional I/O
var data = file.read('file.txt');
doSomethingWith(data);
Something is not right here
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7. Traditional I/O
var data = file.read('file.txt');
// zzzZZzzz FAIL!
doSomethingWith(data);
Don’t waste those cycles!
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8. Async I/O
file.read('file.txt', function(data) {
doSomethingWith(data);
}); WIN ✔
doSomethingElse();
No need to wait for the disk,
do something else meanwhile!
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9. The Present
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10. Quality components
• V8 (developed for google chrome)
• libev (event loop)
• libeio (non-block posix, thread pool)
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11. CommonJS 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
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12. Child processes
child.js
var child = process.createChildProcess('sh',
['-c', 'echo hello; sleep 1; echo world;']);
child.addListener('data', function (chunk) {
p(chunk);
});
$ node child.js
"hellon"
# 1 sec delay
"worldn"
null
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13. Http Server
var http = require('http');
http.createServer(function(req, res) {
setTimeout(function() {
res.writeHeader(200, {'Content-Type': 'text/plain'});
res.write('Thanks for waiting!');
res.close();
}, 1000);
}).listen(4000);
$ curl localhost:4000
# 1 sec delay
Thanks for waiting!
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14. Tcp Server
var tcp = require('tcp');
tcp.createServer(function(socket) {
socket.addListener('connect', function() {
socket.write("Hi, How Are You?n> ");
});
socket.addListener('data', function(data) {
socket.write(data);
});
}).listen(4000);
$ nc localhost 4000
Hi, How Are You?
> Great!
Great!
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15. DNS
dns.js
var dns = require('dns');
dns.resolve4('nodejs.org', function(err, addr, ttl,
cname) {
p(addr, ttl, cname);
});
$ node dns.js
[ '97.107.132.72' ]
84279
'nodejs.org'
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16. Watch File
watch.js
process.watchFile(__filename, function() {
puts('You changed me!');
process.exit();
});
$ node watch.js
# edit watch.js
You changed me!
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17. ECMAScript 5
• Getters / setters
var a = {};
a.__defineGetter__('foo', function() {
return 'bar';
});
puts(a.foo);
• Array: filter, forEach, reduce, etc.
• JSON.stringify(), JSON.parse() & more [1]
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18. There is only 1 thread
file.read('file.txt', function(data) {
// Will never fire
});
while (true) {
// this blocks the entire process
}
Good for conceptual simplicity
Bad for CPU-bound algorithms
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19. The Future
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20. Web workers
• Multiple node processes that do
interprocess communication
• CPU-bound algorithms can run separately
• Multiple CPU cores can be used efficiently
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21. Streams
• Node is working towards a unified data
stream interface
• Stream can be readable, writable or both
see [2]
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22. Readable Streams
• events: ‘data’, ‘end’
• methods: pause(), resume()
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23. Writeable Streams
• events: ‘drain’, ‘close’
• methods: write(), close()
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24. Stream Redirection
http.createServer(function (req, res) {
// Open writable file system
var temp = fs.openTemporaryFile();
// Pump the request into the temp file.
stream.pump(req, temp, function (err) {
if (err) throw err;
p('sweet!');
});
});
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25. Better Socket Support
• Support for unix sockets, socketpair(), pipe()
• Pass sockets between processes ➠ load
balance requests between web workers
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26. Debugger
• V8 support debugging
• Node has a few bugs with exposing the
debugger, those need fixing
• Command line node-debug REPL tool
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27. Readline and Curses
• Bindings for JavaScript
• Would allow to build better command line
tools
• Goal should be to write a screen clone in
node
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28. HTML and XML parsing
• HTML is a major protocol
• Node should be able to parse dirty XML/
HTML
• Should be a SAX-style parser in pure JS
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29. Support for Windows
• Patches welcome! : )
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30. Hot code reloading
(maybe)
• Reload module during runtime
• Update code without taking server offline
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31. Suitable Applications
• Web frameworks
• Real time
• Crawlers
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32. More Applications
• Process monitoring
• File uploading
• Streaming
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33. Let’s write a chat
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34. Http Chat in 14 LoC
var
http = require('http'),
messages = [];
http.createServer(function(req, res) {
res.writeHeader(200, {'Content-Type' : 'text/plain'});
if (req.url == '/') {
res.write(messages.join("n"));
} else if (req.url !== '/favicon.ico') {
messages.push(decodeURIComponent(req.url.substr(1)));
res.write('ok!');
}
res.close();
}).listen(4000);
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35. Production ready?
• For small systems, yes.
• Perfect example: Comet server
• Usually few bugs, but API is still changing
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36. Questions?
✎ @felixge
$ http://debuggable.com/
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37. Links
[1]: http://wiki.github.com/ry/node/ecma-5mozilla-
features-implemented-in-v8
[2]: http://wiki.github.com/ry/node/streams
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38. Bonus Slides!
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39. Dirty
JavaScript Views Memory Store
Disk Persistence Speed > Safety
Dirty
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40. A scriptable key-value store
• Let your business logic and your data share the same
memory / process
• Network = OVERHEAD - Avoid whenever possible
• V8 makes it very fast
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41. How fast?
• Set: 3-5 million docs / sec
• Get: 40-50 million docs / sec
(on my laptop - your milage may vary)
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42. Benchmarks
Do your own!
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43. Disk persistence
• Append-only log
• Writes happen every x-Sec or every x-
Records
• Callbacks fire after disk write succeeded
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44. Dirty Hello World
hello.js
var
Dirty = require('dirty').Dirty,
posts = new Dirty('test.dirty');
posts.add({hello: 'dirty world!'});
posts.set('my-key', {looks: 'nice'});
$ node hello.js
$ cat test.dirty
{"hello":"dirty world!","_key":"3b8f86..."}
{"looks":"nice","_key":"my-key"}
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45. Reloading from Disk
hello.js
var
Dirty = require('dirty').Dirty,
posts = new Dirty('test.dirty');
posts.load(function() {
p(posts.get('my-key'));
});
$ node hello.js
{"looks": "nice", "_key": "my-key"}
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46. Use Cases
• Small projects (db < memory)
• Rapid prototyping
• Add HTTP/TCP interface and scale
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47. http://github.com/felixge/node-dirty
(or google for “dirty felixge”)
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