why do we break apis? first answers from developers

Why Do We Break APIs?First Answers from Developers

Laerte Xavier, André Hora, Marco Tulio ValenteFederal University of Minas Gerais, Brazil

SANER 2017 ERA Track

2

Breaking API contracts is a common practice!

API changes break compatiblity

28%Historical and Impact Analysis of API Breaking Changes:

A Large-Scale Study, SANER, 20173

4

The rate of breaking changes increases over time!

Historical and Impact Analysis of API Breaking Changes: A Large-Scale Study, SANER, 2017

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What specific reasons motivate API breaking changes?

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RQ1: Why do developers break API contracts?

RQ2: Are developers aware of the impact of breaking changes on client applications?

Research Questions

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TOP-317GITHUB JAVA LIBRARIES

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TOP-317GITHUB JAVA LIBRARIES

90LIBRARIES WITH MORE

THAN 50 BREAKING CHANGES

9

TOP-31790

49EMAILS FROM MAJOR

CONTRIBUTORS

GITHUB JAVA LIBRARIES

LIBRARIES WITH MORE THAN 50 BREAKING

CHANGES

49EMAILS

SENT 10

49EMAILS

SENT

14ANSWERSRECEIVED 11

49EMAILS

SENT

14ANSWERSRECEIVED

28%RESPONSE

RATE 12

13

49EMAILS

SENT

14ANSWERSRECEIVED

7EMAILS

SELECTED RESPONSE

RATE

28%

14

15

16

17

18

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RQ1: Why do developers break API contracts?

RQ2: Are developers aware of the impact of breaking changes on client applications?

Research Questions

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Five main reasons

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“The change leads to better and more developer-friendly code (for example, to more fluent code).” [D2]

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“The classes/methods/fields are not removed all, they are just refactored to a better package signature.” [D6]

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“Bugfix. For example some of the items shouldn’t be accessible and were made private.” [D3]

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“We switched the assertion library on which the library was based.” [D4]

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“It’s a deliberate policy. bitcoinj has never done a 1.0 release that would have posted API stability.” [D7]

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RQ1: Why do developers break API contracts?

RQ2: Are developers aware of the impact of breaking changes on client applications?

Research Questions

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SEVENANSWERS

28

FIVEAWARE

SEVENANSWERS

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FIVEAWARE

TWOUNCLEAR

SEVENANSWERS

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FIVEAWARE

TWOUNCLEAR

SEVENANSWERS

“Once one client asked to use @Deprecated on old methods, but we simply

don’t have enough resources to maintain all deprecated

methods.” [D2]

31

FIVEAWARE

TWOUNCLEAR

SEVENANSWERS

“Yes. But we are not Spring yet. [...] Being a

small-to-middle library has it’s benefits.” [D2]

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Five main reasons why developers break APIs

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Five main reasons why developers break APIs

Most developers are aware of the impact

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Five main reasons why developers break APIs

Most developers are aware of the impact

In some cases, they adopt strategies to mitigate

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Five main reasons why developers break APIs

Most developers are aware of the impact

In some cases, they adopt strategies to mitigate

New study contacting developers right after a commit with a breaking change

Why do you break APIs?

36

Why do you break APIs?

37

Are you aware about the impact?

Why Do We Break APIs?First Answers from Developers

Laerte Xavier, André Hora, Marco Tulio ValenteFederal University of Minas Gerais, Brazil

SANER 2017 ERA Track