Meine Slides vom 21.05.2011 bei der devcon Hamburg. Der code von der demo danach ist hier: https://gist.github.com/9f551235cdab4301e780

1. node.js
Eine praktische Einführung
Felix Geisendörfer
21.05.2011 (v7)

2. @felixge
Twitter / GitHub / IRC

3. Datei Uploads & Umwandlung als Infrastruktur
Service für Web- & Mobile-Apps.
- The app we run in production

4. Core Contributor
&
Module Author
node-mysql node-formidable
- Joined the mailing list in June 26, 2009
- When I joined there where #24 people
- First patch in September 2009
- Now mailing list has > 3400 members

5. node @ devcon?
Who is doing JavaScript?
Has used node?
Is using node in production (an app that is running this very moment)?

6. “Easy” and “Scalable” : )
Node makes Hard -> Easy, Easy -> Hard

7. Node.js
• Gestarted durch Ryan Dahl
• Google’s V8 JavaScript engine (kein DOM)
• Modul System, Dateisystem, Netzwerk, Http und
Dns

8. Installing
$ git clone
git://github.com/joyent/node.git
$ cd node
$ ./configure
$ make install

9. Ingredients
libeio libev
c-ares V8
http_parser
libev: event loop
libeio: async I/O
c-ares: non-blocking dns
http_parser: 40 bytes / connection
v8: google’s JS engine

10. Serverseitiges JavaScript

11. Serverseitiges JavaScript
• Netscape LiveWire (1996)
• Rhino (1997)
• 50+ weitere Plattformen
LiveWire to script enterprise appliances
Rhino was done because the plan was to rewrite netscape entirely in Java (Javagator)
Wikipedia lists 50+ other plattform since then

12. Was war das Problem?
• Langsame Engines
• Wenig Interesse an JavaScript bis ~2005
• Bessere alternativen

13. Warum JavaScript?
3 Gründe
Why not python / ruby / java

14. #1 - Die Guten Seiten
World’s most misunderstood programming language
Closures
JSON
Flexible

15. V8 (Chrome)
SpiderMonkey (Firefox) JavaScriptCore (Safari)
#2 - JS Engine Wars
Chakra (IE9) Carakan (Opera)
siehe: arewefastyet.com
War on terror
Spider Monkey: TraceMonkey, JägerMonkey
JavaScriptCore: SquirrelFish Extreme / Nitro

16. #3 - Kein I/O im core

17. Non-blocking I/O

18. 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);
Dauer = SUM(A, B)
Disk / Network access is 1.000-1.000.000 slower than CPU / Ram access

19. I/O im Verhältnis
• CPU / Ram: Sehr Schnell
• Disk / Netzwerk: 1.000x - 1.000.000x
langsamer

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);
});
Dauer = MAX(A, B)

21. Non-Blocking I/O
• I/O Aufgaben an den Kernel weitergeben
und events durch file descriptor polling
erkannt (select, epoll, kqueue, etc.)
• Thread pool für alles andere

22. Single Threaded
var a = [];
function first() {
a.push(1);
a.push(2);
}
function second() {
a.push(3);
a.push(4);
}
setTimeout(first, 10);
setTimeout(second, 10);

23. Single Threaded
var a = [];
function first() {
a.push(1); • [1, 2, 3, 4] ?
a.push(2);
}
• [3, 4, 1, 2] ?
function second() {
a.push(3);
a.push(4); • [1, 3, 2, 4] ?
}
setTimeout(first, 10);
• BAD_ACCESS ?
setTimeout(second, 10);
Who thinks:
- Answer not on the list?
- A possible?
- B possible?
- C possible?

24. Single Threaded
var a = [];
function first() {
a.push(1); • [1, 2, 3, 4]
a.push(2);
}
• [3, 4, 1, 2]
function second() {
a.push(3);
a.push(4); • [1, 3, 2, 4]
}
setTimeout(first, 10);
• BAD_ACCESS
setTimeout(second, 10);
Who thinks:
- Answer not on the list?
- A possible?
- B possible?
- C possible?

25. Anwendungsbereiche

26. DIRT
• Data Intensive
• Real Time
Daten verlieren = schlecht
Daten verzögern = noch schlechter

27. Beispiele (DIRT)
• Chat Server
• Twitter
• Telephony

28. Andere Beispiele
• Single Page Apps
• File uploads
• Unix tools parallel laufen lassen
http://teddziuba.com/2011/02/the-case-against-queues.html
“I love asynchronous stuff as much as the next guy, but think of a queue like Java: it
encourages large swaths of mediocre programmers to overengineer shit, and it keeps
systems administrators in business by giving them something to respond to at 4AM.” -- Ted
Dziuba

29. Interessante Projekte

30. Package management

31. 2000+ Module in npm
+10 neue / Tag

32. Web Frameworks
• Express.js (Sinatra clone)
• Fab.js (Mind-bending & awesome)

33. Socket.IO
var http = require('http');
var io = require('socket.io');
var server = http.createServer();
server.listen(80);
var socket = io.listen(server);
socket.on('connection', function(client){
client.send('hi');
client.on('message', function(){ … })
client.on('disconnect', function(){ … })
});
Server

34. Socket.IO
<script src="http://{node_server_url}/socket.io/socket.io.js" />
<script>
var socket = new io.Socket({node_server_url});
socket.connect();
socket.on('connect', function(){ … })
socket.on('message', function(){ … })
socket.on('disconnect', function(){ … })
</script>
Client

35. Socket.IO
• WebSocket
• Adobe® Flash® Socket
• AJAX long polling
• AJAX multipart streaming
• Forever Iframe
• JSONP Polling
Chooses most capable transport at runtime!

36. Ready for production?

37. Unsere Erfahrungen
mit transloadit.com
• Über 200.000 Datei Uploads
• Mehrere TB an Daten verarbeitet
• Keine bugs, Memory usage 30 - 80 MB

38. Community

39. Benevolent Dictator For Life
Ryan Dahl
Wohlwollender Diktator auf Lebenszeit

40. Community
• Mailing list (nodejs, nodejs-dev)
• IRC (#node.js) - 500+ User online
4000+ people on mailing list
500+ people on IRC

41. Hosting

42. Probleme

43. db.query('SELECT A', function() {
db.query('SELECT B', function() {
db.query('SELECT C', function() {
db.query('SELECT D', function() {
// WTF
});
});
});
});

44. Probleme
• Stack traces gehen an der event loop
Grenze verloren
• Aufgaben auf mehrere Prozesse verteilen
• V8: 1- 1.9 GB heap limit / GC Probleme
+ not as many libraries as the ruby ecosystem

45. Questions?

46. Mehr Infos
nodeguide.com
/
nodebeginner.org

47. Node.js Workshop in Köln
Freitag, 10. Juni
nodecologne.eventbrite.com
15% Discount mit code ‘devcon’

48. Questions?