1. node.js

2. Concurrency?

3. In system level it is achieved by Time Division Multiplexing

4. 1. Process Forking

6. Process Forking

10. a. Context switching between threads is faster than that between processes

11. a. Context switching between threads is faster than that between processes a. Context switching between threads is not free

12. b. Multiple threads within a process share state as well as memory and other resources

13. b. Multiple threads within a process share state as well as memory and other resources b. Call stack associated with a thread is > 0 bytes

15. c. Scaling is achieved by creating a new thread per connection.

16. c. Scaling is achieved by creating a new thread per connection. c. For massive concurrency we can not use one O/S thread per connection.

18. d. Creating a thread is faster than creating a process.

19. d. Creating a thread is faster than creating a process. d. Thread creation is not really cheap, and in some systems it's costlier than forking.

21. Threaded model drops in performance as concurrency increases

22. 1. Using Java NIO/MQ for asynchronous calls, I/O operations. 2. Using green threads 3. Thread pooling

23. But it needs expert knowledge and system level hacking in some cases.

24. Concurrency?

25. 3. Event Loop

27. a. Long running routines will block the loop

28. Event loop can not support long running blocking routines

29. What is long running?

30. I/O

31. I/O latency eats CPU cycles

32. Non blocking, asynchronous I/O

33. node.js

34. Provides a simplistic API to write extremely scalable event-driven server

36. Evented non/blocking i/o

37. Built on V8 Engine

38. CommonJS standard

39. Evented non blocking platform to write high concurrent applications

40. How it works?

42. Non blocking I/O

43. Interrupts

44. How to use it?

45. // Old blocking style resultSet = database.select("something"); // wait... tap tap tap doStuff(resultSet);

46. // New non-blocking style database.select("something", function(resultSet) { // called on completion doStuff(resultSet); });

47. var sys = require('sys'), http = require('http'); http.createServer(function (req, res) { setTimeout(function () { res.writeHead(200, {'Content-Type': 'text/plain'}); res.end('Hello World!'); }, 2000); }).listen(8000); sys.puts('Server running at http://127.0.0.1:8000/'); Hello World!

48. Where can we use it?

50. real time application

51. socket apps

52. ...

54. Loads of available modules

55. It's JS, easy to install and deploy

57. var sys = require("sys"); sys.puts("Happy Hacking!");