Streams are awesome.

1. Streams are awesome.
@sh1mmer

2. Tom Hughes-Croucher
@sh1mmer

5. Scalable Server-Side Code with JavaScript
Node Up and Running
Tom Hughes-Croucher
http://ofps.oreilly.com/titles/9781449398583/
http://shop.oreilly.com/product/0636920015956.do

6. Client → ServerServer → DB
Computation Computation
@sh1mmer

7. Non event-driven
frontend
@sh1mmer

8. @sh1mmer

9. Server
@sh1mmer

10. Request
@sh1mmer

11. @sh1mmer

12. Event-driven frontend
@sh1mmer

13. Place-
holder
@sh1mmer

14. @sh1mmer

15. Shared
Work
Resources
@sh1mmer

16. Memory operations
@sh1mmer

17. var x = "I am a string"
~1ns Running 1 instruction
2ns Data from l1 cpu cache
5ns Data from l2 cpu cache
80ns Data from ram
@sh1mmer

18. @sh1mmer

19. Mobile data latency
@sh1mmer

20. @sh1mmer

21. 100 Blue Whales
Cat
@sh1mmer

22. Node.js Streams
@sh1mmer

23. Streams
• Readable
• Pause
• Resume
• data event
• Writable
• Write
• Pipe

24. Event Loop Fail
node.cc
add-ons v8
libuv
libev iocp

25. nextTick
Event Loop Fail
nextTick
Run stuff
TCP
Conn node.cc
FS
Read
add-ons v8
TCP
Conn
v8
func libuv
v8 TCP
func Conn
libev iocp
v8 FS
func Read
FS
Read

26. stream.pause()
@sh1mmer

27. nextTick
Event Loop Fail
nextTick
stream.pause()
TCP
Conn node.cc
FS
Read
add-ons v8
TCP
Conn
v8
func libuv
v8 TCP
func Conn
libev iocp
v8 FS
func Read
FS
Read

28. New Streams
• Writable
• Same (hooray!)
• Readable
• Configure buffer waterline
• readable event
• read(len) -> returns data
• Pipe
• Doesn't mix with direct access

29. Node.js Domains
@sh1mmer

30. var d = domain.create();
function readSomeFile(filename, cb) {
fs.readFile(filename, 'utf8', d.bind(function(er, data) {
// if this throws, it will also be passed to the domain
return cb(er, data ? JSON.parse(data) : null);
}));
}
d.on('error', function(er) {
// an error occurred somewhere.
// if we throw it now, it will crash the program
// with the normal line number and stack message.
});
@sh1mmer

31. Questions!
@sh1mmer