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Technical Debt - PHPBenelux

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  • 1. Technical Debt Elizabeth Naramore PHPBenelux January 28, 2011 1
  • 2. Technical Debt: What is it? 2
  • 3. Technical Debt:Why should we care? 3
  • 4. "Shipping first time code is like going intodebt. A little debt speeds development so long as it is paid back promptly with a rewrite... The danger occurs when the debt is notrepaid. Every minute spent on non-quite-right code counts as interest on that debt. --Ward Cunningham, 1992 4
  • 5. "I think that there were plenty of cases where people would rush software out the door and learn things but never putthat learning back into the program, and that by analogy, was borrowing money thinking that you never had to pay it back.... eventually all your income goes to interest and your purchasing power goes to zero." 5
  • 6. What is technical debt? Code or practices that will hinder your progress in the future. 6
  • 7. Why should we care? Too much technical debt can cripple your team or organization. 7
  • 8. You have technical debt if you have: lack of documentation untested code suppressed errors unshared knowledge between teams or people confusing code, inconsistencies, "workarounds" local changes youve not committed 8
  • 9. Or, if you have:code that doesnt follow coding standardsnon-existent or improperly used version controlunstable deployment processduplicate code blocksindividual code ownership3rd party software that needs updated or patched 9
  • 10. Guess what? 10
  • 11. We all have it. 11
  • 12. Dont panic. 12
  • 13. Some technical debt is ok. 13
  • 14. It might make sense if:It lets you hit a deadlineIt lets you test an experimental featureThe code is rarely touchedYou are coding based on reasonable expectationsIt allows you to extend startup moneyYour code is at the end of the life-cycle 14
  • 15. This is also known as prudent technical debt. 15
  • 16. So when istechnical debt not ok? 16
  • 17. So when is technical debt not ok?All the other times. 17
  • 18. This is also known as reckless technical debt. 18
  • 19. Sometimes we knowwe are taking shortcuts, but we do it anyway. 19
  • 20. This is also known as deliberate technical debt. 20
  • 21. Sometimes we dont know any better, orthe debt is not our fault. 21
  • 22. This debt could come from:inexperienced team memberschanging project requirementspost-release retrospectives rdsecurity patches or updates from 3 parties 22
  • 23. This is also known as inadvertent technical debt. 23
  • 24. 4 ways to classify technical debt: Prudent vs. RecklessDeliberate vs. Inadvertent 24
  • 25. Martin Fowlers Quadrant 25
  • 26. Martin Fowlers Quadrant 26
  • 27. By minimizing deliberate debt,you make it easier to handleinadvertent debt. 27
  • 28. So now that we know what it is,what do we do with it? 28
  • 29. We tackle our debt with D.E.B.T. (see what I did there?) 29
  • 30. DiscoverEstimateBreak DownTask & Track 30
  • 31. DiscoverWhere is our technical debt? 31
  • 32. Discover Where is our technical debt?Ask the developers on your teamUse the checklist mentioned earlierUse software like PHPUnderControl or Sonar 32
  • 33. Discoverlack of documentationuntested codesuppressed errorsunshared knowledge between teams or peopleconfusing code, inconsistencies, "workarounds"local changes youve not committed 33
  • 34. Discovercode that doesnt follow coding standardsnon-existent or improperly used version controlunstable deployment processduplicate code blocksindividual code ownership3rd party software that needs updated or patched 34
  • 35. Discover Where is our technical debt?Ask the developers on your teamUse the checklist mentioned earlierUse software like PHPUnderControl or Sonar 35
  • 36. Discoverhttp://phpundercontrol.org/ 36
  • 37. DiscoverPhpUnderControl uses:- PHPUnit- phpDocumentor- PHP_CodeSniffer 37
  • 38. Discoverhttp://sonarsource.com 38
  • 39. Discover Sonar uses:- PHPUnit- PHP_CodeSniffer- PHPDepend- PHPMD- phpcpd 39
  • 40. EstimateWhat will it take to pay it off? How badly is it hurting us? 40
  • 41. Estimate The Sonar FormulaDebt(in man days)= cost_to_fix_duplications + cost_to_fix_violations + cost_to_comment_public_API + cost_to_fix_uncovered_complexity +cost_to_bring_complexity_below_threshold + cost_to_cut_cycles_at_package_level 41
  • 42. EstimateThe Sonar Formula 42
  • 43. Estimatehttp://nemo.sonarsource.org 43
  • 44. Estimate 44
  • 45. Estimate But how much is it costing us? The Simple-ish Formula Amount of the “loan” = cost to fix“Interest Rate” = Adverse impact on development 45
  • 46. Estimate Quantifying is hard.OK to use other techniques to generalize the interest rate. 46
  • 47. EstimateUse estimation technique that works for youGet input and buy-in from the team 47
  • 48. Break it DownWhat do we do with it? 48
  • 49. Break Down What do we do with it?Every task breaks down into 2 categories:1. Debts where we continue paying interest2. Debts where we pay the principal 49
  • 50. Task and TrackHow can we make it visible? 50
  • 51. Task and Track How can we make it visible?Add it to bug tracker, task board, etc. 51
  • 52. Paying it Off 52
  • 53. Paying it OffFocus on higher interest rate items first OR Focus on small ticket items first. 53
  • 54. Paying it OffDedicate time for technical debt reduction.● Use time right after a release● Tech debt iteration● Time each day for tech debt● Refactor as you go● Use off-season time 54
  • 55. Paying it OffKeep track of your progress. 55
  • 56. Preventing Technical Debt● Break past habits● Group consensus & commitment● Teach your “children” well● Never file for bankruptcy● Live within your means● Anticipate your needs 56
  • 57. A Few Words About CHANGEMANAGEMENT 57
  • 58. Change Management 58
  • 59. Change Management 59
  • 60. Change Management1. Direct the Rider 60
  • 61. Change Management2. Motivate the Elephant 61
  • 62. Change Management3. Shape the Path 62
  • 63. Make sure to see:PHP UnderControl:http://phpundercontrol.orgSonar:http://www.sonarsource.com/(plus tech debt plugin) 63
  • 64. http://joind.in/talk/view/2418 64
  • 65. Want to contact me? http://naramore.net/blog @ElizabethN elizabeth@naramore.net Freenode IRC: ElizabethN THANKS! Image used with permission from Martin Fowler 65