The only way developers can finish projects on-time and under-budget is by taking on Technical Debt. Taking shortcuts, using quick fixes, and writing unmaintainable code builds up a technical debt that get the project delivered today. Tomorrow, there will be a reckoning, as development costs spiral and progress grinds to a halt. This talk helps you embrace the debt, love the cowboys, and gives you a way to make repayments.

1. Falling in Love with
Technical Debt
@rjrodger
senecajs.org
Tuesday 5 November 2013

2. How did the
Romans do
Long Division?
Tuesday 5 November 2013

3. L rem XII
LXXII MMMDCXII
Tuesday 5 November 2013

4. How did the
Romans do
Addition?
Tuesday 5 November 2013

5. IV + XI = ?
Tuesday 5 November 2013

6. IV + XI = ?
1. Normalize: IV → IIII
2. Concatenate: IIII + XI → IIIIXI
3. Sort, descending: IIIIXI → XIIIII
4. Reduce: XIIIII → XV
Tuesday 5 November 2013

7. How did the
Romans do
Subtraction?
Tuesday 5 November 2013

8. XXIV - XV = ?
Tuesday 5 November 2013

9. XXIV - XV = ?
1. Normalize: XXIV → XXIIII
2. Eliminate: XXIIII - XV → XIIII - V
3. Expand: XIIII - V → VIIIIIIIII - V
4. Repeat 2 and 3 until no moves left
5. Reduce: IIIIIIIII → IX
Tuesday 5 November 2013

10. How did the
Romans do
Multiplication?
Tuesday 5 November 2013

11. III × VI = ?
Tuesday 5 November 2013

12. III × VI = ?
bit shifting
Tuesday 5 November 2013

13. III × VI = ?
bit shifting
III → 3
VI → 6 → 110
Tuesday 5 November 2013

14. III × VI = ?
bit shifting
III → 3
VI → 6 → 110
Tuesday 5 November 2013
3 × 001 × 0 = 0
3 × 010 × 1 = 6
3 × 100 × 1 = 12
18

15. III × VI = ?
bit shifting
III → 3
VI → 6 → 110
Tuesday 5 November 2013
3 × 001 × 0 = 0
3 × 010 × 1 = 6
3 × 100 × 1 = 12
18

16. III × VI = ?
bit shifting
III → 3
VI → 6 → 110
Tuesday 5 November 2013
3 × 001 × 0 = 0
3 × 010 × 1 = 6
3 × 100 × 1 = 12
18

17. How did the
Romans do
Division?
Tuesday 5 November 2013

18. Tuesday 5 November 2013

19. they didn't
Tuesday 5 November 2013

20. Tuesday 5 November 2013

21. Roman Numerals
have
Technical Debt
Tuesday 5 November 2013

22. http://akvo.org/blog/the-ball-of-mud-transition/
Tuesday 5 November 2013

23. Tuesday 5 November 2013

24. The JavaScript Date Object
var today = new Date( 2013, 10, 30)
console.log(today)
Sat Nov 30 2013 00:00:00 GMT+0000
Tuesday 5 November 2013

25. Not all
Technical Debt
is created equal
Tuesday 5 November 2013

26. Intentional
"A good plan, violently executed now,
is better than a perfect plan next week."
Tuesday 5 November 2013

27. Unintentional
Tuesday 5 November 2013

28. Inherent
Tuesday 5 November 2013

29. Incidental
Tuesday 5 November 2013

30. 2x2 Matrix!
unintentional
Tuesday 5 November 2013
live with it
you are a bad
person
unknown
unknowns
incidental
intentional
deliberate
choice
inherent

31. Tuesday 5 November 2013

32. Tuesday 5 November 2013

33. Tuesday 5 November 2013

34. NTSC 1941 Standard:
Black+White only
Signal encodes Brightness
Each Channel gets 6Mhz
Happy Days!
Tuesday 5 November 2013

35. Color Television
Three Colors: Red, Green, Blue
Each Color needs 3Mhz
You only have 6Mhz
and you need 9Mhz!
Technical Debt FTW
Tuesday 5 November 2013

36. You can't Break the
old Black+White TVs
Tuesday 5 November 2013

37. We must send the old brightness signal
White Light =
30% Red
59% Green
11% Blue
Send White, Red and Blue
Tuesday 5 November 2013

38. You need to embed the
color signals inside
the brightness signal
Tuesday 5 November 2013

39. Color TV circuits are
more complicated
than they should be.
Tuesday 5 November 2013

40. How do you Reduce
Technical Debt?
Tuesday 5 November 2013

41. Things that
Don't Work
Tuesday 5 November 2013

42. Unit Testing
(or any other sort)
Tuesday 5 November 2013

43. Objects
Tuesday 5 November 2013

44. Design
Tuesday 5 November 2013

45. Process
Tuesday 5 November 2013

46. Mitigation
As Good as it Gets
Tuesday 5 November 2013

47. Conform
Tuesday 5 November 2013

48. Rebel
Tuesday 5 November 2013

49. Evolve
Tuesday 5 November 2013

50. Cells
•Do one job
•Death is natural
•Use messages
•Really small
Tuesday 5 November 2013

51. Micro Services
•Do one job
•One feature
•Death is natural •kill and restart
•Use messages •No shared state
•Really small
Tuesday 5 November 2013
•100 lines of code

52. Examples
User
Data
Image
Resize
Encrypt
Password
Tuesday 5 November 2013
Business
Rule
Send
Email
Parse
Format
Monitor

53. how do you route
messages?
Pattern Matching
Tuesday 5 November 2013

54. The user Service
some messages
// load a user's data by name
{ user:"load", name:"alice" }
// login user - load and check password
{ user:"login", name:"alice", pass:"123"}
github.com/rjrodger/websummit2013
senecajs.org
Tuesday 5 November 2013

55. user_load action
var users = {
alice: {name:"alice", pass:"123"},
bob:
{name:"bob",
pass:"abc"},
}
function user_load( args, done ) {
// callback( err, result )
done( null, users[args.name] )
}
Tuesday 5 November 2013

56. user_login action
function user_login( args, done ) {
user_load(
{ name:args.name },
function(err,user){
if( err || !user ) return done(err);
if( user.pass == args.pass )
return done( null, user );
return done();
})
}
Tuesday 5 November 2013

57. Run user Service
using Seneca
require("seneca")()
.add({ user:"load" }, user_load)
.add({ user:"login" }, user_login)
.listen(8000)
$ node user.js
$ curl "http://localhost:8000/act ?
user=login & name=alice & pass=123"
{ "name":"alice", "pass":"123" }
Tuesday 5 November 2013

58. What Happens?
•Easy to change - just rewrite!
•Easy to scale - run more instances
•Easy to reason about - just messages
•Easy to make robust - kill and restart!
•Easy to build - natural units of work
Tuesday 5 November 2013

59. Technical Debt?
lower interest rate!
See github for
scaling and adapting
github.com/rjrodger/websummit2013
senecajs.org
Tuesday 5 November 2013

60. Try this at Home!
•Java: twitter.github.io/finagle
•Ruby: sinatrarb.com
•Node: senecajs.org
Tuesday 5 November 2013

61. Technical Debt
•overwhelms every other factor
•should drive your architecture
•can be mitigated with awareness
Tuesday 5 November 2013

62. Tuesday 5 November 2013

63. Thank You!
@rjrodger
senecajs.org
Tuesday 5 November 2013