The document studies how developers react to API deprecations in a Smalltalk ecosystem. It finds that 14% of deprecated methods and 7% of classes triggered ripple effects in other projects. While most projects quickly adapted, some ripple effects lasted years. Recommendation messages were often missing or unhelpful. The study highlights the need for better deprecation guidelines and tool support to minimize disruption from API changes.

1. How Do Developers React to
API Deprecation?
The Case of a Smalltalk Ecosystem
Romain Robbes Mircea Lungu
David Röthlisberger Software Composition Group
University of Chile University of Bern
FSE, 2012

2. Software
A Natural Ecosystem
Ecosystems

3. A collection of software systems which are developed
and co-evolve in the same environment.
A Software Ecosystem

4. A collection of software systems which are developed
and co-evolve in the same environment.
Activity (high)
Dependency
A Software Ecosystem Activity (low)
size

5. A collection of software systems which are developed
and co-evolve in the same environment.
A Software Ecosystem

6. [...] where is MOLabelShape,
why was it deleted?? I use it
and now is gone!!! I even had
a specialization of it [...]

7. Deprecating a class in the ecosystem
FillInTheBlank UIManager
(deprecated) (recommended)

8. Tool Support...

9. Tool Support...
Empirical
Evidence
First!

10. API Changes
Providers
Classes
Methods

11. API Changes
Ripple-inducing changes
Providers
• addition of provider Classes
• change of provider Methods
• removal of provider

12. API Changes
Ripple-inducing changes
Providers
• addition of provider Classes
• change of provider Methods
• removal of provider
Deprecation of provider
= lower bounds

13. API Deprecation:
Empirical Study
1. Frequency
2. Magnitude
3. Duration
4. Adaptation

14. SqueakSource
8 years { Contributors:
Projects:
Classes:
Commits:
2.300
2.500
95.000
110.000
LOC: 600.000.000

15. How to model the history of
SqueakSource?
System
History
Ecosystem
Version 1
Version 2
Version n
Version i
History
History
... ...
History
... System
Version
History
Added
Artifacts ...
Removed
Provided Required

16. Ecco - a lighweight model
System
History
Ecosystem
Version 1
Version 2
Version n
Version i
History
History
... ...
History
... System
Version
History
Added
Artifacts ...
Removed
Provided Required

17. Methodology
1. Generate list of candidates (577 methods,
186 classes)
2. Filter methods removed less than 3 times
3. Manual inspection of the rest of the
candidates
4. Answer RQ for all the true deprecation-
based ripples

18. Manual Inspection
+ Retrieve changes involving deprecation
+ Display changes in Ripple Browser
x2
+ Validate impacted projects
+ Track replacement methods
= 180 methods + 20 classes

19. Results

20. }
Results
Frequency
Magnitude
Duration
Adaptations

21. RQ1: Frequency of ripple effects triggered by
API deprecation
14% of deprecated methods triggered ripple effects.
7% of deprecated classes triggered ripple effects.

22. RQ1: Frequency of ripple effects triggered by
API deprecation
14% of deprecated methods triggered ripple effects.
7% of deprecated classes triggered ripple effects.
developers do not know their clients and program
⤷ defensively

23. RQ1: Frequency of ripple effects triggered by
API deprecation
14% of deprecated methods triggered ripple effects.
7% of deprecated classes triggered ripple effects.
developers do not know their clients and program
⤷ defensively
⤷ clients may still be unaware of deprecations

24. RQ2: Magnitude of ripple effects triggered by
API deprecation
reacting projects
(i) reacting projects (ii) reacting pack
80
● ●
120
100
60
80
● ●
40
●
●
60
●
● ●
●
●
● ●
● ●
●
40
●
20
●
●
20
0
0

25. RQ2: Magnitude of ripple effects triggered by
API deprecation
reacting projects
(i) reacting projects (ii) reacting pack
80
● ●
120
100
60
80
● ●
40
●
●
60
●
● ●
●
●
● ●
● ●
●
40
●
20
●
●
20
0
0
⤷ several projects usually react
⤷ the impact on the ecosystem can be very large

26. Viewing the magnitude from other angles
60
40
20
0
Projects Developers Packages Commits
A project reacting to an API change ...

27. Viewing the magnitude from other angles
60
40
20
0
Projects Developers Packages Commits
A project reacting to an API change ...
⤷ may involve several developers and packages

28. Viewing the magnitude from other angles
60
40
20
0
Projects Developers Packages Commits
A project reacting to an API change ...
⤷ may involve several developers and packages
⤷ is often a process involving several commits

29. RQ3: Duration of ripple effects triggered by API
deprecation
(i) reaction Time Adaptation timetime days)
(ii) adaptation (in
●
For a given project, the
60
800
adaptation time is the
50
●
●
time between the first
●
600
40
reaction and the last
●
reaction to the API
30
400
●
change ●
●
20
●
200
10
0
0

30. RQ3: Duration of ripple effects triggered by API
deprecation
(i) reaction Time Adaptation timetime days)
(ii) adaptation (in
●
For a given project, the
60
800
adaptation time is the
50
●
●
time between the first
●
600
40
reaction and the last
●
reaction to the API
30
400
●
change ●
●
20
●
200
10
0
0
most projects are quick to react and adapt;
⤷ but not all are

31. RQ3: Duration of ripple effects triggered by API
deprecation
(i) reaction Time Adaptation timetime days)
(ii) adaptation (in
●
For a given project, the
60
800
adaptation time is the
50
●
●
time between the first
●
600
40
reaction and the last
●
reaction to the API
30
400
●
change ●
●
20
●
200
10
0
0
most projects are quick to react and adapt;
⤷ but not all are
On the scale of the ecosystem, some ripple
⤷ effects lasted for years.

32. RQ4: Do all projects adapt to API changes?
70 66%
53
40%
35
20%
18
0
All Active No counter-
projects reactions

33. RQ4: Do all projects adapt to API changes?
70 66%
53
40%
35
20%
18
0
All Active No counter-
projects reactions
Why so few
reacting projects?

34. RQ4: Do all projects adapt to API changes?
70 66%
53
40%
35
20%
18
0
All Active No counter-
projects reactions
Why so few Dead or stagnant
reacting projects? projects?

35. RQ4: Do all projects adapt to API changes?
70 66%
53
40%
35
20%
18
0
All Active No counter-
projects reactions
Why so few
reacting projects?

36. RQ4: Do all projects adapt to API changes?
70 66%
53
40%
35
20%
18
0
All Active No counter-
projects reactions
Why so few Forks in the
reacting projects? ecosystem?

37. RQ4: Do all projects adapt to API changes?
70 66%
53
40%
35
20%
18
0
All Active No counter-
projects reactions
Why so few
reacting projects?

38. RQ4: Do all projects adapt to API changes?
70 66%
53
40%
35
20%
18
0
All Active No counter-
projects reactions

39. RQ4: Do all projects adapt to API changes?
70 66%
53
40%
35
20%
18
0
All Active No counter-
projects reactions
common reasons for not reacting are stagnancy,
⤷ forks, but also freezed dependencies and unawareness.

40. RQ5: Consistency of adaptations
addEntity: was replaced by:
add:
addModel:
addObject:
addAll:
addSibling:
0 20 40 60 80

41. RQ5: Consistency of adaptations
Frequency of most
addEntity: was replaced by: frequent replacement
Probability of most likely replacement
100
add:
addModel:
80
60
addObject:
40
addAll:
20
addSibling:
0
0 20 40 60 80

42. RQ5: Consistency of adaptations
Frequency of most
addEntity: was replaced by: frequent replacement
Probability of most likely replacement
100
add:
addModel:
80
60
addObject:
40
addAll:
20
addSibling:
0
0 20 40 60 80
⤷ Many API deprecation have similar reactions

43. RQ5: Consistency of adaptations
Frequency of most
addEntity: was replaced by: frequent replacement
Probability of most likely replacement
100
add:
addModel:
80
60
addObject:
40
addAll:
20
addSibling:
0
0 20 40 60 80
⤷ Many API deprecation have similar reactions
⤷ 16% of deprecations had a systematic replacement

44. RQ6: Were deprecation messages useful?
foo: x
self deprecated: ‘use method bar instead’

45. RQ6: Were deprecation messages useful?
foo: x
self deprecated: ‘use method bar instead’
We categorized deprecation messages according to
whether developer followed the recommendation.

46. RQ6: Were deprecation messages useful?
foo: x
self deprecated: ‘use method bar instead’
We categorized deprecation messages according to
whether developer followed the recommendation.
Mostly followed: if “X” most people did X
Somewhat followed: most people did Y, but others did X
Not followed: most people did Y, Z ...
Missing: no recommendation, vague recommendation.

47. RQ6: Were deprecation messages useful?
foo: x
self deprecated: ‘use method bar instead’
We categorized deprecation messages according to
whether developer followed the recommendation.
Mostly followed: if “X” most people did X
Somewhat followed: most people did Y, but others did X
Not followed: most people did Y, Z ...
Missing: no recommendation, vague recommendation.
self deprecated: ‘removed functionality’
self deprecated: ‘use canvas API’
self deprecated: ‘ugly method, do not call it!’

48. RQ6: Were deprecation messages useful?
50
46.8%
40.4%
38
25
13 7.4%
5.3%
0
Recommendation ...
Mostly Somewhat Not Missing
followed followed followed

49. RQ6: Were deprecation messages useful?
50
46.8%
40.4%
38
25
13 7.4%
5.3%
0
Recommendation ...
Mostly Somewhat Not Missing
followed followed followed
⤷ half of deprecation messages are missing or not useful

50. Threats to validity
Code duplication, name clashes introduce noise
We only consider explicit deprecation so far
Partially manual analysis
Single case study with peculiarities:
– Dynamically typed language (Smalltalk)
– Fork in the community

51. Related work
Empirical studies:
– Studies of API changes and client evolution
[Dig & Johnson, 2005]
– Studies of ripple effects at the system level
[Yau et al., 1978; Black, 2001]
Adapting to API changes:
– Replaying refactorings [Henkel & Diwan 2004;
Ekman & Asklund 2005; Dig et al. 2007]
– Detecting systematic changes
[Kim and Notkin 2009]
– Adapting to evolving frameworks
[Dagenais & Robillard 2008; Shäfer et al. 2008]
– Filtering irrelevant changes
[Holmes and Walker, 2010]

52. Conclusions and implications
System
History
Ecosystem
Version 1
Version 2
Version n
Version i
History
History
... ...
History
... System
Version
History
Added
Artifacts ...
Removed
Provided Required

53. Conclusions and implications
System
History
Ecosystem
Version 1
Version 2
Version n
Version i
History
History
... ...
History
... System
Version
History
Added
Artifacts ...
Removed
Provided Required
⤷ The quality of deprecation guidelines should be improved

54. Conclusions and implications
System
History
Ecosystem
Version 1
Version 2
Version n
Version i
History
History
... ...
History
... System
Version
History
Added
Artifacts ...
Removed
Provided Required
⤷ The quality of deprecation guidelines should be improved
⤷ Some API deprecations have a large impact

55. Conclusions and implications
System
History
Ecosystem
Version 1
Version 2
Version n
Version i
History
History
... ...
History
... System
Version
History
Added
Artifacts ...
Removed
Provided Required
⤷ The quality of deprecation guidelines should be improved
⤷ Some API deprecations have a large impact
⤷ Developers do not know how their software is used

56. Conclusions and implications
System
History
Ecosystem
Version 1
Version 2
Version n
Version i
History
History
... ...
History
... System
Version
History
Added
Artifacts ...
Removed
Provided Required
⤷ The quality of deprecation guidelines should be improved
⤷ Some API deprecations have a large impact
⤷ Developers do not know how their software is used
⤷ Reactions to API changes can be partially automated

57. Conclusions and implications
System
History
Ecosystem
Version 1
Version 2
Version n
Version i
History
History
... ...
History
... System
Version
History
Added
Artifacts ...
Removed
Provided Required
⤷ The quality of deprecation guidelines should be improved
⤷ Some API deprecations have a large impact
⤷ Developers do not know how their software is used
⤷ Reactions to API changes can be partially automated
⤷ Tool support is needed to help with API changes

58. Conclusions and implications
System
History
Ecosystem
Version 1
Version 2
Version n
Version i
History
History
... ...
History
... System
Version
History
Added
Artifacts ...
Removed
Provided Required
⤷ The quality of deprecation guidelines should be improved
⤷ Some API deprecations have a large impact
⤷ Developers do not know how their software is used
⤷ Reactions to API changes can be partially automated
⤷ Tool support is needed to help with API changes

59. THE END
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