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A COMMAND PROMPT TALK

A COMMAND PROMPT TALK. Node.js and postgres. An Introductory Glance With Live Code, Later. 2010 AURYNN SHAW, COMMAND PROMPT INC. Hi!. What is Node.js. Fast Pure event-driven server-side javascript programming environment. Ew, javascript. Built on Google’s V8

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A COMMAND PROMPT TALK

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  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

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