This is a version of the talk given at Dev Bootcamp in Chicago. Technical Debt has become a catch-all phrase for any code that needs to be re-worked. Much like Refactoring has become a catch-all phrase for any activity that involves changing code. These fundamental misunderstandings and comfortable yet mis-applied metaphors have resulted in a plethora of poor decisions. What is technical debt? What is not technical debt? Why should we care? What is the cost of misunderstanding? What do we do about it? Doc discusses the origins of the metaphor, what it means today, and how we properly identify and manage technical debt.

1. #DevBootcamp / #TechnicalDebtTrap / @DocOnDev
The
technical Debt
Trap

2. #DevBootcamp / #TechnicalDebtTrap / @DocOnDev
Doc Norton, CEO
doc@wearecto2.com
@DocOnDev

3. #DevBootcamp / #TechnicalDebtTrap / @DocOnDev
what is technical debt?

4. #DevBootcamp / #TechnicalDebtTrap / @DocOnDev
– Ward Cunningham
OOPSLA ‘92
Shipping first time code is like
going into debt.

5. #DevBootcamp / #TechnicalDebtTrap / @DocOnDev
Shipping first time code is like
going into debt. A little debt
speeds development so long as
it is paid back promptly with a
rewrite.
– Ward Cunningham
OOPSLA ‘92

6. #DevBootcamp / #TechnicalDebtTrap / @DocOnDev
Shipping first time code is like
going into debt. A little debt
speeds development so long as
it is paid back promptly with a
rewrite.
The danger occurs when the
debt is not repaid. Every minute
spent on not-quite-right code
counts as interest on that debt.
– Ward Cunningham
OOPSLA ‘92

7. #DevBootcamp / #TechnicalDebtTrap / @DocOnDev
The danger occurs
when the debt is not
repaid. Every minute
spent on not-quite-
right code counts as
interest on that debt.
– Ward Cunningham
OOPSLA ‘92

8. #DevBootcamp / #TechnicalDebtTrap / @DocOnDev
The danger occurs
when the debt is not
repaid. Every minute
spent on not-quite-
right code counts as
interest on that debt.
– Ward Cunningham
OOPSLA ‘92

9. #DevBootcamp / #TechnicalDebtTrap / @DocOnDev
Technical debt is

10. #DevBootcamp / #TechnicalDebtTrap / @DocOnDev
Technical debt is
good

11. #DevBootcamp / #TechnicalDebtTrap / @DocOnDev
Technical debt is good

12. #DevBootcamp / #TechnicalDebtTrap / @DocOnDev
Technical debt is
good

13. #DevBootcamp / #TechnicalDebtTrap / @DocOnDev
Technical debt is
a strategic decision

14. #DevBootcamp / #TechnicalDebtTrap / @DocOnDev
Technical debt is
a strategic decision
• Allow for Rapid Delivery
• To Elicit Quick Feedback
• And Correct Design

15. #DevBootcamp / #TechnicalDebtTrap / @DocOnDev
technical debt is
an indication of learning

16. #DevBootcamp / #TechnicalDebtTrap / @DocOnDev
technical debt is
an indication of learning
• Now know what you need
• Implementation doesn’t match

17. #DevBootcamp / #TechnicalDebtTrap / @DocOnDev
technical debt is a metaphor

18. #DevBootcamp / #TechnicalDebtTrap / @DocOnDev
metaphors rock
we reason by analogy
Building on a
weak foundation
Puts pressure on our design
Can’t keep running at this pace
It’s raining men
(hallelujah)

19. #DevBootcamp / #TechnicalDebtTrap / @DocOnDev
metaphorphosis
when metaphors go wrong
Credit CardSHORT-TERM
Long-Term
Return on
Investment
OPERATIONALHOME LOAN
Loan Shark
PRAGMATIC
LEVERAGE
Intentional AUTO LOAN
FRAUDULENT
VOLUNTARY
PYRAMID SCHEME
Prudent
Student Loan
HIGH INTEREST
INADVERTENT
RECKLESS DEBT IN
THE THIRD
QUADRANT

20. #DevBootcamp / #TechnicalDebtTrap / @DocOnDev
metaphorphosis
when metaphors go wrong
“quick and dirty”
- Martin Fowler
“sloppy”
- David Laribee
“just hack it in”
- Steve McConnell
“CUT A LOT OF CORNERS”
- James Shore

21. #DevBootcamp / #TechnicalDebtTrap / @DocOnDev
technical debt quadrant
Reckless
Inadvertent
Prudent
Deliberate
“We don’t have time
for design”
“We must ship now and
deal with
consequences”
“Now we know how we
should have done it”
“What’s Layering?”

22. #DevBootcamp / #TechnicalDebtTrap / @DocOnDev
– Ward Cunningham
Youtube ‘09
[Many] have explained
the debt metaphor and
confused it with the
idea that you could
write code poorly with
the intention of doing a
good job later.

23. #DevBootcamp / #TechnicalDebtTrap / @DocOnDev
– Ward Cunningham
Youtube ‘09
confused the
debt metaphor
with the idea that
you could write
code poorly

24. #DevBootcamp / #TechnicalDebtTrap / @DocOnDev
– Ward Cunningham
Youtube ‘09
The ability to pay back
debt [...] depends upon
you writing code that is
clean enough to be
able to refactor as you
come to understand
your problem.

25. #DevBootcamp / #TechnicalDebtTrap / @DocOnDev
– Ward Cunningham
Youtube ‘09
The ability to pay back
debt [...] depends upon
you writing code that is
clean enough to be
able to refactor as you
come to understand
your problem.

26. #DevBootcamp / #TechnicalDebtTrap / @DocOnDev
– Ward Cunningham
twitter ‘09
Dirty code is to
technical debt as the
pawn broker is to
financial debt.

27. #DevBootcamp / #TechnicalDebtTrap / @DocOnDev
– Ward Cunningham
twitter ‘09
Dirty code is to
technical debt as the
pawn broker is to
financial debt.
Don’t think you are
ever going to get your
code back.

28. #DevBootcamp / #TechnicalDebtTrap / @DocOnDev
technical debt?
Ask yourself…

29. #DevBootcamp / #TechnicalDebtTrap / @DocOnDev
technical debt?
Ask yourself…
• Is the code clean?
• Is the code tested?
• Is there a learning objective or event?
• Is there a plan for payback?
• Is the business truly informed?

30. #DevBootcamp / #TechnicalDebtTrap / @DocOnDev
technical debt?
If you say no to even one…
• Is the code clean?
• Is the code tested?
• Is there a learning objective or event?
• Is there a plan for payback?
• Is the business truly informed?

31. #DevBootcamp / #TechnicalDebtTrap / @DocOnDev
technical debt?
If you say no to even one…
• Is the code clean?
• Is the code tested?
• Is there a learning objective or event?
• Is there a plan for payback?
• Is the business truly informed?
... then you don’t have Technical Debt

32. #DevBootcamp / #TechnicalDebtTrap / @DocOnDev
mess (noun)

33. #DevBootcamp / #TechnicalDebtTrap / @DocOnDev
mess (noun)
• Disorderly accumulation, heap, or jumble
• A state of embarrassing confusion
• An unpleasant or difficult situation

34. #DevBootcamp / #TechnicalDebtTrap / @DocOnDev
cruft (noun)

35. #DevBootcamp / #TechnicalDebtTrap / @DocOnDev
cruft (noun)
• An unpleasant substance
• The result of shoddy construction
• Redundant, old or improperly written code

36. #DevBootcamp / #TechnicalDebtTrap / @DocOnDev
But, It’s Just
semantics

37. #DevBootcamp / #TechnicalDebtTrap / @DocOnDev
It’s not Just
semantics

38. #DevBootcamp / #TechnicalDebtTrap / @DocOnDev
It’s not Just
semantics
Technical Debt is Good

39. #DevBootcamp / #TechnicalDebtTrap / @DocOnDev
It’s not Just
semantics
Technical Debt is GoodQuick and Dirty is Technical Debt

40. #DevBootcamp / #TechnicalDebtTrap / @DocOnDev
It’s not Just
semantics
Quick and Dirty is Good

41. #DevBootcamp / #TechnicalDebtTrap / @DocOnDev
It’s not Just
semantics
Quick and Dirty is Good

42. #DevBootcamp / #TechnicalDebtTrap / @DocOnDev
technical debt quadrant
Reckless
Inadvertent
Prudent
Deliberate
“We don’t have time
for design”
“We must ship now and
deal with
consequences”
“Now we know how we
should have done it”
“What’s Layering?”

43. #DevBootcamp / #TechnicalDebtTrap / @DocOnDev
technical debt quadrant
Reckless
Inadvertent
Prudent
Deliberate
“We don’t have time
for design”
“Let’s deploy and
gather more
information”
“Now we know how we
should have done it”
“What’s Layering?”

44. #DevBootcamp / #TechnicalDebtTrap / @DocOnDev
technical debt in other fields

45. #DevBootcamp / #TechnicalDebtTrap / @DocOnDev
technical debt in other fields

46. #DevBootcamp / #TechnicalDebtTrap / @DocOnDev
Technical Debt in other fields

47. #DevBootcamp / #TechnicalDebtTrap / @DocOnDev
Technical Debt in other fields

48. #DevBootcamp / #TechnicalDebtTrap / @DocOnDev
technical debt in other fields

49. #DevBootcamp / #TechnicalDebtTrap / @DocOnDev
RECKLESS AND DELIBERATE
technical debt in other fields

50. #DevBootcamp / #TechnicalDebtTrap / @DocOnDev
RECKLESS AND DELIBERATE
RECKLESS AND DELIBERATE
technical debt in other fields

51. #DevBootcamp / #TechnicalDebtTrap / @DocOnDev
RECKLESS AND DELIBERATE
RECKLESS AND DELIBERATE
RECKLESS AND INADVERTENT
technical debt in other fields

52. #DevBootcamp / #TechnicalDebtTrap / @DocOnDev
technical debt quadrant
Reckless
Inadvertent
Prudent
Deliberate
“We don’t have time
for design”
“Let’s deploy and
gather more
information”
“Now we know how we
should have done it”
“What’s Layering?”

53. #DevBootcamp / #TechnicalDebtTrap / @DocOnDev
technical debt quadrant
Reckless
Inadvertent
Prudent
Deliberate
“We don’t have time
for design”
“Let’s deploy and
gather more
information”
“Now we know how we
should have done it”
“What’s Layering?”
IRRESPONSIBLE

54. #DevBootcamp / #TechnicalDebtTrap / @DocOnDev
technical debt quadrant
Reckless
Inadvertent
Prudent
Deliberate
“We don’t have time
for design”
“Let’s deploy and
gather more
information”
“Now we know how we
should have done it”
“What’s Layering?”
IRRESPONSIBLE
INCOMPETENT

55. #DevBootcamp / #TechnicalDebtTrap / @DocOnDev
technical debt quadrant
Reckless
Inadvertent
Prudent
Deliberate
“We don’t have time
for design”
“Let’s deploy and
gather more
information”
“Now we know how we
should have done it”
“What’s Layering?”
IRRESPONSIBLE
INCOMPETENT
TECHNICAL
DEBT

56. #DevBootcamp / #TechnicalDebtTrap / @DocOnDev
cruft or debt?

57. #DevBootcamp / #TechnicalDebtTrap / @DocOnDev
DataSet aDs, qDs;
aDs = _dbConnector.UpdateAgentList();
qDs = _dbConnector.GetQueueList();
foreach (DataTable aTable in aDs.Tables) {
foreach (DataRow aRow in aTable.Rows) {
foreach (DataColumn aColumn in aTable.Columns) {
DataSet asDs = _dbConnector.GetAgentSkills(aRow[aColumn].ToString());//AgentId
foreach (DataTable asTable in asDs.Tables) {
foreach (DataRow asRow in asTable.Rows) {
foreach (DataColumn asColumn in asTable.Columns) {
foreach (DataTable qTable in qDs.Tables) {
foreach (DataRow qRow in qTable.Rows) {
foreach (DataColumn qColumn in qTable.Columns) {
DataSet sqDs = _dbConnector.GetSkillsForQueue(qRow[qColumn].ToString());
foreach (DataTable sqTable in sqDs.Tables) {
foreach (DataRow sqRow in sqTable.Rows) {
foreach (DataColumn sqColumn in sqTable.Columns) {
foreach (string skill in sqRow[sqColumn].ToString().Split(paramDelimStr)) {
if (skill == asRow[asColumn].ToString()) {
try {
_dbConnector.SetAgentQueueSkill(aRow[aColumn].ToString(),
qRow[qColumn].ToString(),
skill);
}
catch { continue; }
}
}
}
}
}
}
}
}
}
}
}
}
}
}
cruft or debt?

58. #DevBootcamp / #TechnicalDebtTrap / @DocOnDev
DataSet aDs, qDs;
aDs = _dbConnector.UpdateAgentList();
qDs = _dbConnector.GetQueueList();
foreach (DataTable aTable in aDs.Tables) {
foreach (DataRow aRow in aTable.Rows) {
foreach (DataColumn aColumn in aTable.Columns) {
DataSet asDs = _dbConnector.GetAgentSkills(aRow[aColumn].ToString());//AgentId
foreach (DataTable asTable in asDs.Tables) {
foreach (DataRow asRow in asTable.Rows) {
foreach (DataColumn asColumn in asTable.Columns) {
foreach (DataTable qTable in qDs.Tables) {
foreach (DataRow qRow in qTable.Rows) {
foreach (DataColumn qColumn in qTable.Columns) {
DataSet sqDs = _dbConnector.GetSkillsForQueue(qRow[qColumn].ToString());
foreach (DataTable sqTable in sqDs.Tables) {
foreach (DataRow sqRow in sqTable.Rows) {
foreach (DataColumn sqColumn in sqTable.Columns) {
foreach (string skill in sqRow[sqColumn].ToString().Split(paramDelimStr)) {
if (skill == asRow[asColumn].ToString()) {
try {
_dbConnector.SetAgentQueueSkill(aRow[aColumn].ToString(),
qRow[qColumn].ToString(),
skill);
}
catch { continue; }
}
}
}
}
}
}
}
}
}
}
}
}
}
}

59. #DevBootcamp / #TechnicalDebtTrap / @DocOnDev
DataSet aDs, qDs;
aDs = _dbConnector.UpdateAgentList();
qDs = _dbConnector.GetQueueList();
foreach (DataTable aTable in aDs.Tables) {
foreach (DataRow aRow in aTable.Rows) {
foreach (DataColumn aColumn in aTable.Columns) {
DataSet asDs = _dbConnector.GetAgentSkills(aRow[aColumn].ToString());//AgentId
foreach (DataTable asTable in asDs.Tables) {
foreach (DataRow asRow in asTable.Rows) {
foreach (DataColumn asColumn in asTable.Columns) {
foreach (DataTable qTable in qDs.Tables) {
foreach (DataRow qRow in qTable.Rows) {
foreach (DataColumn qColumn in qTable.Columns) {
DataSet sqDs = _dbConnector.GetSkillsForQueue(qRow[qColumn].ToString());
foreach (DataTable sqTable in sqDs.Tables) {
foreach (DataRow sqRow in sqTable.Rows) {
foreach (DataColumn sqColumn in sqTable.Columns) {
foreach (string skill in sqRow[sqColumn].ToString().Split(paramDelimStr)) {
if (skill == asRow[asColumn].ToString()) {
try {
_dbConnector.SetAgentQueueSkill(aRow[aColumn].ToString(),
qRow[qColumn].ToString(),
skill);
}
catch { continue; }
}
} } } } } } } } } } } } }

60. #DevBootcamp / #TechnicalDebtTrap / @DocOnDev
DataSet aDs, qDs, asDs, sqDs;
aDs = _dbConnector.UpdateAgentList();
qDs = _dbConnector.GetQueueList();
foreach (DataRow aRow in aDS.Tables[0].Rows) {
String agentID = aRow[“AgentId”].ToString();
asDs = _dbConnector.GetAgentSkills(agentID);
foreach (DataRow asRow in asDs.Tables[0].Rows) {
String agentSkill = asRow[“Skill”].ToString();
foreach (DataRow qRow in qDs.Tables[0].Rows) {
queueName = qRow[“QueueName”].ToString();
sqDs = _dbConnector.GetSkillsForQueue(queueName);
foreach (DataRow sqRow in sqDs.Tables[0].Rows) {
foreach (string skill in sqRow[“Skills”].ToString().Split(paramDelimStr)) {
if (skill == agentSkill) {
try { _dbConnector.SetAgentQueueSkill(agentID, queueName, skill); }
catch { continue; }
} } } } } }

61. #DevBootcamp / #TechnicalDebtTrap / @DocOnDev
AgentList agents = new AgentList(_dbConnector.UpdateAgentList());
QueueList queues = new QueueList(_dbConnector.GetQueueList());
foreach (Agent agent in agents) {
foreach (Skill agentSkill in agent.skills) {
foreach (Queue queue in queues) {
foreach (Skill queueSkill in queue.skills.Where(x => x == agentSkill)) {
try {_dbConnector.SetAgentQueueSkill(agent.agentID, queue.name, agentSkill); }
catch { continue; }
}
}
}
}

62. #DevBootcamp / #TechnicalDebtTrap / @DocOnDev

63. #DevBootcamp / #TechnicalDebtTrap / @DocOnDev
if ((customer.state == “AL” && customer.type ==
CustomerType.GENERAL_AGENT && customer.revenue > 100000)
|| (customer.type == CustomerType.RETRO_AGENT &&
(customer.state == “WI” || customer.state == “IL”))
|| (customer.type == CustomerType.FED_MANAGEMENT &&
customer.revenue > 150000)) { ... }
cruft or debt?

64. #DevBootcamp / #TechnicalDebtTrap / @DocOnDev
// If customer is Federally Regulated
if ((customer.state == “AL” && customer.type ==
CustomerType.GENERAL_AGENT && customer.revenue > 100000)
|| (customer.type == CustomerType.RETRO_AGENT &&
(customer.state == “WI” || customer.state == “IL”))
|| (customer.type == CustomerType.FED_MANAGEMENT &&
customer.revenue > 150000)) { ... }

65. #DevBootcamp / #TechnicalDebtTrap / @DocOnDev
if (customer.isFederallyRegulated()) { ... }

66. #DevBootcamp / #TechnicalDebtTrap / @DocOnDev
double getSpeed() {
switch (_type) {
case EUROPEAN:
return getBaseSpeed();
case AFRICAN:
return getBaseSpeed() - getLoadFactor() * _numberOfCoconuts;
case NORWEGIAN_BLUE:
return (_isNailed) ? 0 : getBaseSpeed(_voltage);
}
throw new RuntimeException ("Should be unreachable");
}
http://www.refactoring.com/catalog/replaceConditionalWithPolymorphism.html
cruft or debt?

67. #DevBootcamp / #TechnicalDebtTrap / @DocOnDev
class Swallow ...
double getSpeed() { return getBaseSpeed(); }
end class
class EuropeanSwallow ...
end class
class AfricanSwallow ...
double getSpeed() { return super.getSpeed - coconutLoad(); }
double coconutLoad() { return getLoadFactor() * _numberOfCoconuts; }
end class
class NorwegianSwallow ...
double getSpeed() { return (_isNailed) ? 0 : getBaseSpeed(_voltage); }
end class

68. #DevBootcamp / #TechnicalDebtTrap / @DocOnDev
cruft is a bad decision

69. #DevBootcamp / #TechnicalDebtTrap / @DocOnDev
cruft is a bad decision
• You are a professional developer
• You’re going to create unintentional cruft
• You have to clean up the existing cruft

70. #DevBootcamp / #TechnicalDebtTrap / @DocOnDev
The Trap

71. #DevBootcamp / #TechnicalDebtTrap / @DocOnDev
The Trap
• Precedent for speed over quality
• Expectation of increased velocity
• Cruft slows you down
• Must write more cruft to keep up
• Ask permission to do your job correctly

72. #DevBootcamp / #TechnicalDebtTrap / @DocOnDev
failing strategies

73. #DevBootcamp / #TechnicalDebtTrap / @DocOnDev
failing strategies

75. #DevBootcamp / #TechnicalDebtTrap / @DocOnDev
winning strategy
Clean Constantly

76. #DevBootcamp / #TechnicalDebtTrap / @DocOnDev
winning strategy
Clean Constantly
• Never make an intentional mess
• Monitor your “Technical Debt”
• Follow the Boy Scout Rule
• Remember quality is your responsibility

77. #DevBootcamp / #TechnicalDebtTrap / @DocOnDev
winning strategy
Clean Constantly
• Never make an intentional mess
• Monitor your “Technical Debt”
• Follow the Boy Scout Rule
• Remember quality is your responsibility
• NEVER ask permission to do your job correctly

78. #DevBootcamp / #TechnicalDebtTrap / @DocOnDev
Monitor your cruft

79. #DevBootcamp / #TechnicalDebtTrap / @DocOnDev
Monitor your cruft
• Code Coverage
• Code Complexity
• Coupling
• Maintainability
• Monitor Trends, Not Points

80. #DevBootcamp / #TechnicalDebtTrap / @DocOnDev
review
Technical Debt
Cruft

81. #DevBootcamp / #TechnicalDebtTrap / @DocOnDev
review
Technical Debt
• A strategic design decision
• Requires business to be informed
• Includes a pay-back plan
Cruft
• Happens
• Needs to be monitored and cleaned
• Is NOT Technical Debt

82. #DevBootcamp / #TechnicalDebtTrap / @DocOnDev
review
Technical Debt
• A strategic design decision
• Requires business to be informed
• Includes a pay-back plan
Cruft
• Happens
• Needs to be monitored and cleaned
• Is NOT Technical Debt
NEVER
ask
perm
issio
n
to
do
yo
ur
jo
b
co
rrectly

83. #DevBootcamp / #TechnicalDebtTrap / @DocOnDev
comments
or
questions?
Doc Norton, CEO
doc@wearecto2.com
@DocOnDev

84. #DevBootcamp / #TechnicalDebtTrap / @DocOnDev
Thank You!
Doc Norton, CEO
doc@wearecto2.com
@DocOnDev

85. #DevBootcamp / #TechnicalDebtTrap / @DocOnDev
The
technical Debt
Trap

86. #DevBootcamp / #TechnicalDebtTrap / @DocOnDev
• OOPSLA 92 Paper - http://dl.acm.org/citation.cfm?
id=157715, http://c2.com/doc/oopsla92.html
• Ward Cunningham Technical Debt Video - http://
www.youtube.com/watch?
v=pqeJFYwnkjE&feature=player_embedded
• Ward Cunningham Twitter - http://twitter.com/
WardCunningham/status/3742903303
• Technical Debt Quadrant - http://martinfowler.com/
bliki/TechnicalDebtQuadrant.html
• James Shore - http://jamesshore.com/Blog/
CardMeeting/Voluntary-Technical-Debt.html
• Martin Fowler - http://www.martinfowler.com/bliki/
TechnicalDebt.html
• David Larabee - http://msdn.microsoft.com/en-us/
magazine/ee819135.aspx
• Steve McConnell - http://blogs.construx.com/blogs/
stevemcc/archive/2007/11/01/technical-debt-2.aspx
• Jon Stewart - http://big.assets.huffingtonpost.com/
JonConfused.gif
• Cruft Example 1 - http://thedailywtf.com/Series/
2010/3/CodeSOD.aspx
• Debt Threshold - http://blog.castsoftware.com/wp-
content/uploads/2011/04/Technical-Debt-Software-
Quality1.jpg
• Hardening Sprints - http://blog.castsoftware.com/wp-
content/uploads/2011/04/Technical-Debt-Software-
Quality1.jpg