Talk focused on preparing to apply Agile Engineering Practices on an existing code base. Most existing projects differ in structure and quality compared to greenfield Agile projects. They often suffer from Code Smells, Architectural Smells, and Deployment Smells. Overcoming these in an evolutionary manner is key to paving the way for successful application of Agile Engineering Practices. Failure to do so could lead to stress and counterproductive results. This presentation covers why, what, and how of some useful techniques. Presented at Agile in Business conference at Pune, India, during India Agile Week (Oct 2013).

1. www.unicomlearning.com
India Agile Week-2013
26 October 2013 | Pune
Paving the Way for Agile Engineering Practices
Aman King
Agile Technologist | Agile Coach
ThoughtWorks India | Bangalore
www.agileinbusiness.com

2. www.unicomlearning.com
Paving the Way
for
Agile Engineering
Practices
UNICOM Presents
India Agile Week-2013

3. www.unicomlearning.com
Paving the Way
for
Agile Engineering
Practices
UNICOM Presents
India Agile Week-2013

4. www.unicomlearning.com
Paving the Way
for
Agile Engineering
Practices
UNICOM Presents
India Agile Week-2013

5. www.unicomlearning.com
Paving the Way
for
Agile Engineering
Practices
UNICOM Presents
India Agile Week-2013

6. Exploring Agile Engineering Practices…

7. Exploring Agile Engineering Practices…

8. Exploring Agile Engineering Practices…

9. Exploring Agile Engineering Practices…

10. Exploring Agile Engineering Practices…

11. Agile Engineering
Practices

12. Paving the Way
for
Agile Engineering
Practices

13. Paving the Way
for
Agile Engineering
Practices
Why?

14. Observations
as
Agile Practitioner &
Agile Coach

15. Most code bases are
inherited by teams

16. Most teams starting Agile
adoption have an existing
code base

17. Existing code bases differ
from “Agile” code bases

18. Agile Engineering Practices
cannot be applied as-is
to existing code bases

19. Result?

20. Technical improvements
cannot keep up with Agile
planning, time-boxes &
frequent delivery

21. Everyone stresses out!
Code base worsens with
every iteration!
Agile deemed a failure!

22. Paving the Way
for
Agile Engineering
Practices
What?

23. Removing common
roadblocks

24. Code smells
Architectural smells
Deployment smells

25. Code smells

26. Most common, most offending!
•
•
•
•
•
•
•
•
•
•
Long methods
Long class
Static method calls
Lot of if-else’s, including null checks
Primitive obsession
Multiple assignments to a local variable
Temporal coupling
Fields as temporary variables
Out parameters
Setters!!!

27. Hurt Matrix
Smell
TDD
Refactoring
Pair
Programming
Continuous
Integration
Long methods/class
X
X
X
-
Statics
X
X
-
X
Conditionals
X
X
X
-
Primitive obsession
X
X
-
-
Multiple assignments
X
X
X
-
Methods with side-effects
X
X
X
-
Setters
X
X
X
-

28. Architectural smells

29. Most common, most offending!
•
•
•
•
•
•
•
•
Incorrect responsibility-split across layers
Confusing or inconsistent module structure
Missing Dependency Injection
Abused Dependency Injection
No componentization
Over-componentization
Rewrites: big-bang, either-or, long-lived
Mixed tech stack

30. Hurt Matrix
Smell
TDD
Refactoring
Pair
Programming
Continuous
Integration
Layering
X
X
X
X
Module structure
X
X
X
-
Missing or abused DI
X
X
X
X
Componentization
X
X
X
X
Rewrites
X
X
X
X
Mixed tech stack
X
X
X
X

31. Deployment smells

32. Most common, most offending!
•
•
•
•
•
•
Branching based on release / feature / team
Dependencies not version controlled
Database changes not version controlled
Deployment scripts not version controlled
Shared non-isolated environments
Infrastructure access highly restricted

33. Hurt Matrix
Smell
TDD
Refactoring
Pair
Programming
Continuous
Integration
Branching strategy
-
X
X
X
Untracked dependencies
-
-
X
X
Untracked DB changes
X
X
X
X
Untracked deployment
scripts
-
-
X
X
Shared environments
X
X
X
X
Restricted infrastructure
access
-
-
X
X

34. Paving the Way
for
Agile Engineering
Practices
How?

35. Let’s look at
examples…

36. Code smells

37. Most common, most offending!
•
•
•
•
•
•
•
•
•
•
Long methods
Long class
Static method calls
Lot of if-else’s, including null checks
Primitive obsession
Multiple assignments to a local variable
Temporal coupling
Fields as temporary variables
Out parameters
Setters!!!

38. Most common, most offending!
•
•
•
•
•
•
•
•
•
•
Long methods
Long class
Static method calls
Lot of if-else’s, including null checks
Primitive obsession
Multiple assignments to a local variable
Temporal coupling
Fields as temporary variables
Out parameters
Setters!!!

39. Smelly!

40. TDD Hurt:
Hard to test for
one thing at a
time!

41. Refactoring
Hurt:
Hard to safely
refactor!

42. Failed attempt at IDE refactoring!

43. Pair
Programming
Hurt:
Hard to quickly
understand!
Hard to quickly
debug!

44. What to do?
Smelly Code

45. Smelly Code
Tests for
Smelly Code

47. Smelly Code
Tests for
Smelly Code
Tests for
new Feature

49. Smelly Code
Tests for
Smelly Code
Tests for
new Feature
Add to
Smelly Code

51. Smelly Code
Tests for
Smelly Code
Tests for
new Feature
Add to
Smelly Code
Smellier
Code

52. Let’s back up a bit…

53. Smelly Code
Tests for
Smelly Code
Tests for
new Feature
Add to
Smelly Code
Smellier
Code

54. Smelly Code
Tests for
Smelly Code
Tests for
new Feature
Manual
Refactor to
Less Smelly
Code
Add to
Smelly Code
Smellier
Code

56. Smelly Code
Tests for
Smelly Code
Tests for
new Feature
Manual
Refactor to
Less Smelly
Code
Add to
Smelly Code
Smellier
Code

58. Smelly Code
Tests for
Smelly Code
Tests for
new Feature
Manual
Refactor to
Less Smelly
Code
Add to
Smelly Code
Add to
Refactored
Code
Smellier
Code

60. Smelly Code
Tests for
Smelly Code
Tests for
new Feature
Manual
Refactor to
Less Smelly
Code
Add to
Smelly Code
Add to
Refactored
Code
Refactor to
Less Smelly
Code
Smellier
Code
Cleaner
Code

64. Smelly Code
Tests for
Smelly Code
Tests for
new Feature
Manual
Refactor to
Less Smelly
Code
Pave!
Add to
Smelly Code
Add to
Refactored
Code
Refactor to
Less Smelly
Code
Smellier
Code
Cleaner
Code

65. Most common, most offending!
•
•
•
•
•
•
•
•
•
•
Long methods
Long class
Static method calls
Lot of if-else’s, including null checks
Primitive obsession
Multiple assignments to a local variable
Temporal coupling
Fields as temporary variables
Out parameters
Setters!!!

66. Most common, most offending!
•
•
•
•
•
•
•
•
•
•
Long methods
Long class
Static method calls
Lot of if-else’s, including null checks
Primitive obsession
Multiple assignments to a local variable
Temporal coupling
Fields as temporary variables
Out parameters
Setters!!!

67. Smelly!

68. Pave!

70. Most common, most offending!
•
•
•
•
•
•
•
•
•
•
Long methods
Long class
Static method calls
Lot of if-else’s, including null checks
Primitive obsession
Multiple assignments to a local variable
Temporal coupling
Fields as temporary variables
Out parameters
Setters!!!

71. Smelly!

72. How to
test
different
outcomes?

73. Pave!

75. Architectural smells

76. Most common, most offending!
•
•
•
•
•
•
•
•
Incorrect responsibility-split across layers
Confusing or inconsistent module structure
Missing Dependency Injection
Abused Dependency Injection
No componentization
Over-componentization
Rewrites: big-bang, either-or, long-lived
Mixed tech stack

77. Most common, most offending!
•
•
•
•
•
•
•
•
Incorrect responsibility-split across layers
Confusing or inconsistent module structure
Missing Dependency Injection
Abused Dependency Injection
No componentization
Over-componentization
Rewrites: big-bang, either-or, long-lived
Mixed tech stack

78. Smelly!

79. Pave!

80. Smelly!

82. Two database hits!

83. Pave!

84. More domain driven

85. Most common, most offending!
•
•
•
•
•
•
•
•
Incorrect responsibility-split across layers
Confusing or inconsistent module structure
Missing Dependency Injection
Abused Dependency Injection
No componentization
Over-componentization
Rewrites: big-bang, either-or, long-lived
Mixed tech stack

86. Smelly!

87. Field-based
injection

88. How to inject the
mock?

89. Pave!

92. A
B
C
Spring IoC
D

94. A
B
C
Spring IoC
D
E

99. A
B
C
E
Spring IoC
D

100. A
B
C
E
Spring IoC
D
Is E really
“cross-cutting”
or is it just too
easy to inject?

101. A
High
coupling
B
C
E
Spring IoC
D
Smelly!

102. A
B
C
E
Spring IoC
D
Solution?

103. A
B
C
D
E
Pave!
Spring IoC

104. Deployment smells

105. Most common, most offending!
•
•
•
•
•
•
Branching based on release / feature / team
Dependencies not version controlled
Database changes not version controlled
Deployment scripts not version controlled
Shared non-isolated environments
Infrastructure access highly restricted

106. Most common, most offending!
•
•
•
•
•
•
Branching based on release / feature / team
Dependencies not version controlled
Database changes not version controlled
Deployment scripts not version controlled
Shared non-isolated environments
Infrastructure access highly restricted

107. Smelly!
http://martinfowler.com/bliki/FeatureBranch.html

108. Pave!
http://martinfowler.com/bliki/FeatureToggle.html
http://paulhammant.com/blog/branch_by_abstraction.html

109. Most common, most offending!
•
•
•
•
•
•
Branching based on release / feature / team
Dependencies not version controlled
Database changes not version controlled
Deployment scripts not version controlled
Shared non-isolated environments
Infrastructure access highly restricted

110. Pave!
Dump
current
schema DDL
Introduce a
tool like
Liquibase/
dbdeploy &
commit
initial DDL
script
Similarly for DML
http://www.liquibase.org
http://dbdeploy.com
Further
changes
made only
via
Liquibase/
dbdeploy
scripts
Test the
Liquibase/
dbdeploy
scripts
Commit the
Liquibase/
dbdeploy
scripts

111. Most common, most offending!
•
•
•
•
•
•
Branching based on release / feature / team
Dependencies not version controlled
Database changes not version controlled
Deployment scripts not version controlled
Shared non-isolated environments
Infrastructure access highly restricted

112. Pave!
Automate
deployment
steps with
bash scripts
Commit the
scripts into
a versioncontrolled
repository
http://rubygems.org/gems/chef
http://rubygems.org/gems/puppet
Automate
invoking the
scripts via a
CI tool like
Jenkins/Go
Build
confidence
with
automated
smoke tests
Replace
scripts with
a tool like
Chef/
Puppet

113. Most common, most offending!
•
•
•
•
•
•
Branching based on release / feature / team
Dependencies not version controlled
Database changes not version controlled
Deployment scripts not version controlled
Shared non-isolated environments
Infrastructure access highly restricted

114. Pave!
Identify
volatile
shared
resources
Deploy/
install local
version of
identified
resources
Create stubs
as local
version of
identified
resources
Develop
against local
version of
identified
resources
Regularly
update/sync
local version
of identified
resources
Test end-toend on a true
integrated
environment

115. Paving the Way
for
Agile Engineering
Practices…

116. Is difficult but doable!
Needs some upfront thinking,
planning & implementation.
Can be done alongside business
functionality.

117. Just be alert & prepared…
to pave the way!

118. www.unicomlearning.com
amanking.com
king@thoughtworks.com
India Agile Week-2013
Organized by
UNICOM Trainings & Seminars Pvt. Ltd.
contact@unicomlearning.com
Example code available at
https://github.com/amanking/paving_the_way_talk_companion