A COMMAND PROMPT TALK

1. A COMMAND PROMPT TALK

2. Node.js and postgres • An Introductory Glance • With Live Code, Later 2010 AURYNN SHAW, COMMAND PROMPT INC.

3. Hi!

4. What is Node.js • Fast • Pure event-driven • server-side • javascript programming environment

5. Ew, javascript • Built on Google’s V8 • Runs on modern unix-likes (Linux, OSX, Freebsd, Cygwin) • Speaks network natively, and easily (Hello world is in http!) • Ends up Similar to Python, Perl, Ruby, ETc.

6. Did I mention fast? • Single thread can do many thousands of connections • standard library doesn’t block

7. Did I mention fast? • Single thread can do many thousands of connections • standard library doesn’t block • Keeps the slow tasks from blocking • Keeps the quick tasks quick

8. blocking? # Standard synchronous processing fh = open(“somefile”,”r”) contents = fh.read() # what if somefile is huge, 1GB+ ? print contents

9. Every step waits

10. How is node different?

11. Did I mention fast? • Single thread can do many thousands of connections • standard library doesn’t block • Keeps the slow tasks from blocking • Keeps the quick tasks quick

12. Really good for anything I/O

13. While slow tasks run, node carries on

14. Non-blocking! fs.open(“somefile”, function (fd) { // When the file descriptor gets returned. var buffer = null; fs.read(fd, buffer, length, position, function (e, bytes) { // bytes read are here. // buffer will be not-null. }); });

15. As always, there’s caveats to this

16. Some caveats • node is entirely single-threaded • Event-driven programming is *really* different

17. A maze of callbacks fs.open(“/tmp/hello”, function (fd) { var buffer = null; fs.read(fd, buffer, length, position, function (e, bytes) { // bytes read are here. // buffer will be not-null. }); });

18. Some caveats • node is entirely single-threaded • Event-driven programming is *really* different • Javascript’s prototype model is also really different • The syntax has warts

19. Build a bridge out of her? /* This allows you to kind of inherit properly. */ var o = function () {}; var p = function () { /* Because ‘this’ changes */ var self = this; o.call(this); }; p.prototype = o; p.prototype.constructor = p;

20. So why is this important?

21. Why is it important? • Javascript owns the frontend

22. Why is it important? • Javascript owns the frontend • More jquery and javascript programmers every day

23. Why is it important? • Javascript owns the frontend • More jquery and javascript programmers every day • Javascript is fast

24. Faster every day

25. And now, we can use postgres!

26. When I got here... • postgres.js worked.

27. When I got here... • postgres.js worked. • Used the simple query protocol

28. When I got here... • postgres.js worked. • Used the simple query protocol • Used SQL escape to prevent injection attacks.

29. whyyyy SOURCE: http://www.flickr.com/photos/striatic/2192192956/

30. But it did work!

31. And so I wanted to make it BETTER

32. So, I had to ask,

33. How do I not allow this?

34. Well...

35. to prepare a query • postgres.js Didn’t use libpq.

36. SOURCE: http://www.flickr.com/photos/tanaka/2319325408/

37. to prepare a query • postgres.js Didn’t use libpq. • Speaks pure protocol

38. to prepare a query • postgres.js Didn’t use libpq. • Speaks pure protocol • ...So I had to learn the protocol.

39. Wax on, wax off MONTAGE!

40. Sadly, reality was a lot less exciting

41. Complexity Abounds • Simple protocol sends one message to pg • Easy to queue, internally.

42. REALLY SIMPLE MESSAGE QUEUE QUERY QUERY QUERY QUERY QUERY QUERY RESULTS

43. Really, though • Simple protocol sends one message to PG • Easy to queue, internally. • Prepared statements require at least 5 • Parse, describe, execute, bind, flush

44. THIS TYPE OF QUEUE DOESN’T WORK SYNC EXECUTE BIND DESCRIBE PARSE QUERY QUERY

45. And while all this is happening • You cannot block the main thread • And postgres expects a synchronous request/response • But it does give responses...

46. And while all this is happening • You cannot block the main thread

47. And while all this is happening • You cannot block the main thread • And postgres expects a synchronous request/response

48. And while all this is happening • You cannot block the main thread • And postgres expects a synchronous request/response • But it does give responses...

49. So, we buffer message sets

50. KIND OF LIKE THIS SIMPLE PREPARED GROUP SIMPLE SIMPLE PREPARED GROUP SIMPLE SIMPLE