1. What's so special about Node.js? giancarlo.valente@gmail.com twitter @gncvalente

2. years of front-end programming evolution now on server-side

3. javascript

4. Fundamental videography Ryan Dahl at JS.Conf 2009 show his creature http://jsconf.eu/2009/video_nodejs_by_ryan_dahl.html and also this ... http://vimeo.com/9968301

5. Fundamental videography Douglas Crockford: “Crockford on JavaScript Scene 6: Loopage” August 2010 http://www.yuiblog.com/blog/2010/08/30/ yui-theater-douglas-crockford-crockford-on-javascript -scene-6-loopage-52-min

6. node.js is special

7. What does node.js, nginx, memcached have in common ?

8. a C library called libevent

9. Apache vs Nginx http://blog.webfaction.com/a-little-holiday-present

10. Apache vs Nginx http://blog.webfaction.com/a-little-holiday-present

11. apache uses threads nginx uses an event loop

12. ... it's a different approach on building servers ... with differnt strenghts / weaknesses event loop approach scales better when has to serve many clients with requests that doesn't need so much "data crunching" elaboartion, but a lot of I/O

13. Ryan's idea! node.js is a thin layer that glue 3 libraries togheter: V8 js engine + libev (event loop) + libeio (async I/O)

14. blocking I/O historically all programming languages have blocking I/O

15. but, a problem arise: the very expensive "data processing machine" is not used in a very efficient way

16. multi user systems use of timesharing, in order to make the same computer multiuser

17. in our modern "server side" code, the same thing appens how do we solve this? simple, we do the same thing. We invented the Threads!

18. but now the situation is like this Help !!! web real-time, long running sockets ... I've sent the newsletter with 90% discount !!! traffic jam !

19. has a different approach

20. event loop approach event loop is used from many years in: games graphical UIs ... servers

21. single thread server c1, c2, c3, c4 ---> S ---> I/O

22. multi-thread server c1 ---> T1 ---> I/O c2 ---> T2 ---> I/O c3 ---> T3 ---> I/O c4 ---> T4 ---> I/O

23. thread pool server c9, c5, c1 ---> T1 ---> I/O c10, c6, c2 ---> T2 ---> I/O c11, c7, c3 ---> T3 ---> I/O c12, c8, c4 ---> T4 ---> I/O

24. event loop c1 ---> ST --> async I/O c2 ---> c3 ---> c4 ---> c5 ---> c6 ---> c7 ---> c8 ---> c9 ---> c10 ---> c11 ---> c12 --->

25. so what's the point ... also the browser is mono-thread and works with an event loop

26. when we write setTimeout('timeout_trigger()', 2000) we're not creating a new thread! (as sometimes I've heard ...) but we're subscribing a new event, which will run our callback, 2 seconds from now

27. so ... why all this hype ? who are the most expert professionals in event driven programming with non blocking I/O ?

28. the one that do this from years! front-end developers!

29. accidental evolution of a language (video) http://www.yuiblog.com/blog/2010/08/30/ yui-theater-douglas-crockford-crockford-on-javascript -scene-6-loopage-52-min

30. part 2

31. Do we all jump on the node.js train? maybe sometimes but it's important to understand what are the strenght of node so we can know how and when to use it.

32. alternatives ? yes, but we can talk about them next time ... :)

33. weaknesses monothread (?) (also principal strength point) .. you've to follow the rules non blocking operations, develop in evented style