This document summarizes a study of developer discussions on forums and Stack Overflow about concerns when using web APIs. The researchers analyzed over 92,000 discussions related to 32 popular web APIs across different domains to identify the most discussed topics (RQ1) and how those topics evolved over time (RQ2). They found that a small number of topics dominated each API's discussions, with the top 5 topics making up over 50% on average. They also identified 5 patterns of how topic discussions declined or reoccurred over time. The findings provide insights for both API providers and client developers to better support developers.

1. What Concerns Do Client Developers Have
When Using Web APIs?
An Empirical Study of Developer Forums and Stack Overflow
Pradeep K. Venkatesh Ying Zou Ahmed E. HassanShaohua Wang Feng Zhang

2. Agenda
• Introduction/Background of the work
• Research problem
• What we do?
• Dataset
• Results - RQ’s
• Future work

3. Service Oriented Computing
Organizations Client Applications
• Popularity of service-oriented computing makes companies
to offer their services through Web APIs
• Client applications extensively use these Web APIs to offer
more value-added services

4. Research Problem
Web API Evolution
Fix Bugs Optimize PerformanceIntroduce New
features

5. Research Problem
Web API Evolution
Fix Bugs Optimize PerformanceIntroduce New
features
More
Frequently

6. Research Problem
Web API Evolution
Fix Bugs Optimize PerformanceIntroduce New
features
More
Frequently
Grace period
3 to 6 Months

7. Research Problem
Web API Evolution
Fix Bugs Optimize PerformanceIntroduce New
features
More
Frequently
Grace period
3 to 6 Months
Client Developers often have concerns and difficulties
adapting Web APIs.

8. ‘S
We Want!
• Know the discussions related to web APIs & understand
the common challenges faced by client developers

9. ‘S
We Want!
• Know the discussions related to web APIs & understand
the common challenges faced by client developers
• Make smart recommendation/suggestions to providers &
client developers

10. What We Do?
Developer
Discussions
Mine and Analyze the Developer Discussions

11. What We Do?
Developer
Discussions
Topic
Modelling
Technique
}
Mine and Analyze the Developer Discussions
Identify
Common & Dominant
Discussions

12. What We Do?
Developer
Discussions
Topic
Modelling
Technique
}
Mine and Analyze the Developer Discussions
Identify
Common & Dominant
Discussions
Time
Series
Clustering
Patterns of
Dominant Discussions

13. Dataset
Consists of 32 popular Web APIs from 7 different domains
Business/eCommerce
Data Storage/Sharing
Location Based Services
Mapping Services
Platform/Tools/Utilities
Social Media/Network
Video/Audio Streaming

14. Dataset
Consists of 32 popular Web APIs from 7 different domains
Business/eCommerce
Data Storage/Sharing
Location Based Services
Mapping Services
Platform/Tools/Utilities
Social Media/Network
Video/Audio Streaming
Total Num
ber of Discussions
92,471

15. Research Questions
(RQ1.) What are the most discussed topics related
to Web APIs among client developers?
(RQ2.) What are the evolution patterns of the
most discussed topics?

16. Research Questions
(RQ1.) What are the most discussed topics related
to Web APIs among client developers?
(RQ2.) What are the evolution patterns of the
most discussed topics?

17. RQ1. Analysis Approach
Apply Popular Topic Modelling Technique
• Latent Dirichlet Allocation

18. RQ1. Analysis Approach
Apply Popular Topic Modelling Technique
• Latent Dirichlet Allocation
• Pre-process:
• Removing any code elements <code>….</code>
• Removing all HTML tags <a>, <i>, <a href=“…”/>
• Removing all stop words “a”,”is”,”was”
• Applying stemming on english words to get to their
base form. e.g., “programming”, “programmer” to
base form of “program”

19. RQ1. Analysis Approach
Apply Popular Topic Modelling Technique
• Latent Dirichlet Allocation
• Pre-process:
• Removing any code elements <code>….</code>
• Removing all HTML tags <a>, <i>, <a href=“…”/>
• Removing all stop words “a”,”is”,”was”
• Applying stemming on english words to get to their
base form. e.g., “programming”, “programmer” to
base form of “program”
• Extract 40 Discussions Topics from developer discussions

20. RQ1. Results
• Only Limited Number of Topics Dominate developer
discussions
• Some Dominant Discussions Topics are shared across Web
APIs of each category
• Few Dominant Discussion Topics are Shared across
categories
• E.g., Authentication/Authorization
On average, the five most discussed topics contribute
to over 50% of discussions in each Web API.

21. Research Questions
(RQ1.) What are the most discussed topics related to Web
APIs among client developers?
(RQ2.) What are the evolution patterns of the most
discussed topics?

22. RQ2. Analysis Approach
Apply Hierarchical Time Series Clustering Algorithm

23. RQ2. Analysis Approach
Apply Hierarchical Time Series Clustering Algorithm
1) we sum up the number of discussions per month for
every LDA topic of a Web API;
2) we create a matrix where a row label is a topic of a Web
API and a column label is a time unit (i.e., one month);
3) we convert the matrix to a distance matrix using the
Autocorrelation
4) apply a hierarchical time series clustering algorithm

24. RQ2. Analysis Approach
Apply Hierarchical Time Series Clustering Algorithm
We identify patterns of discussion topics of Web APIs
1) we sum up the number of discussions per month for
every LDA topic of a Web API;
2) we create a matrix where a row label is a topic of a Web
API and a column label is a time unit (i.e., one month);
3) we convert the matrix to a distance matrix using the
Autocorrelation
4) apply a hierarchical time series clustering algorithm

25. RQ2. Results
• Discover five evolution patterns of discussion topics among
client developer discussions

26. RQ2. Results
• Discover five evolution patterns of discussion topics among
client developer discussions
(P1) Persistent topics with the number of discussions DECLINING QUICKLY
(P2) Persistent topics with the number of discussions DECLINING SLOWLY
(P3) Occasional topics with the number of discussions DECLINING QUICKLY
(P4) Occasional topics with the number of discussions DECLINING SLOWLY
(P5) Reoccurring topics
• We conjecture that P2 type are the hardest to deal with

27. RQ2. Results
• Discover five evolution patterns of discussion topics among
client developer discussions
(P1) Persistent topics with the number of discussions DECLINING QUICKLY
(P2) Persistent topics with the number of discussions DECLINING SLOWLY
(P3) Occasional topics with the number of discussions DECLINING QUICKLY
(P4) Occasional topics with the number of discussions DECLINING SLOWLY
(P5) Reoccurring topics
• We conjecture that P2 type are the hardest to deal with
Only a small proportion (i.e. , 4.94%)
of discussions of the topics are in P2, and
the majority (i.e. , 75.45%) of the discussions are P3.

28. Implications of Our Results
Through the findings in RQ1 and RQ2, we observe:
• most of the discussions from client developers are only
limited to a very few topics for a Web API (i.e., on average,
over 50% of the discussions are linked with only 5 topics).
• More importantly, some dominant topics appear
throughout the timeline (i.e., different releases of a Web
API) persistently or reoccurring.
client developers:
feel very frustrated and quit using certain Web APIs.

29. Implications of Our Results
Web API providers:
• can optimize their on-line resources (e.g., documentation,
tutorials, and videos),
• updates of future API releases on the dominant topics
(especially the ones regarding developers’ concerns and
challenges) that appear persistently in a time-efficient way
Client developers:
• can make a better preparation for the dominant topics when
using a Web API if they already have the knowledge of the
history and evolution patterns of the dominant topics.

30. Future work
An immediate follow-up would be an in-depth analysis of
the five patterns.
• to map the release cycle to the five patterns and find what
types of modifications in Web APIs trigger the change in
the concerns of client developers.

32. What Concerns Do Client Developers Have
When Using Web APIs?
An Empirical Study of Developer Forums and StackOverflow
Pradeep K. Venkatesh
Dr. Ying (Jenny) Zou Dr. Ahmed E. Hassan
Shaohua (David) Wang Feng Zhang