Code smells and refactoring have received considerable interest from the academia as well as from the industry in the past two decades. The interest has given birth to various tools, processes, techniques, and practices to identify smells and refactor them. Despite the high interest, architecture smells and corresponding refactorings haven't received as much focus and adoption from the software engineering community. In this presentation, we motivate the need of architecture refactoring, discuss the current related research, and present a few potential research directions for architecture refactoring.

1. Refactoring for Software
Architecture Smells
International
Workshop on
Refactoring
Singapore,Sept.4 2016
Ganesh Samarthyam
CodeOps Technologies
ganesh@codeops.tech
www.codeops.tech
Refactoring for Software
Architecture Smells

2. “Functional Chaos!”

3. City Metaphor for Refactoring
“Cities grow, cities evolve, cities
have parts that simply die while other
parts flourish; each city has to be
renewed in order to meet the needs of its
populace… Software-intensive systems
are like that. They grow, they evolve,
sometimes they wither away, and
sometimes they flourish…”
Grady Booch in the foreword for “Refactoring for Software Design Smells: Managing Technical Debt”, Girish Suryanarayana, Ganesh Samarthyam, Tushar Sharma, Morgan Kaufmann/Elsevier, 2014.

4. Code refactoring
margin = c.getMargin();
if (c instanceof AbstractButton) {
margin = ((AbstractButton)c).getMargin();
} else if (c instanceof JToolBar) {
margin = ((JToolBar)c).getMargin();
} else if (c instanceof JTextComponent) {
margin = ((JTextComponent)c).getMargin();
}

5. Refactoring design smells

6. Earlier (relatively) mature
work

7. Tangles in
JDK

8. Refactoring for Architecture
Smells
Remove one of the dependencies
Change dependency direction
Move one of the dependencies

9. Architectural refactoring

10. Architectural refactoring …

11. Key reasons for architecture
refactoring
Business
needs
Increase
feature
velocity
Address
architecture
decay
Realizing
NFRs
Modernize
Reduce costs

12. Increase feature velocity

13. Reduce costs

14. Address architecture decay

15. Modernize

16. Refactoring Windows

17. Refactoring Windows

18. Refactoring Windows
“A large number of dependencies at the module level
could be reduced and optimized to:
* make modular reasoning of the system more efficient
* maximize parallel development efficiency
* avoid unwanted parallel change interference
* selectively rebuild and retest subsystems effectively”
Refactoring performed to reduce
and optimize dependencies - by
creating and enforcing layering
Source: Kim, Miryung, Thomas Zimmermann, and Nachiappan Nagappan. "An Empirical Study of RefactoringChallenges and Benefits at Microsoft."
IEEE Transactions on Software Engineering 7 (2014): 1-1.

19. Refactoring Windows:
Significant Characteristics
Refactoring decisions made after substantial
analysis of existing dependency structure
Refactoring effort was centralized and top
down with designated team for refactoring
Use of custom refactoring tools (MaX)
and processes (quality gate check)
Source: Kim, Miryung, Thomas Zimmermann, and Nachiappan Nagappan. "An Empirical Study of RefactoringChallenges and Benefits at Microsoft."
IEEE Transactions on Software Engineering 7 (2014): 1-1.

20. Refactoring Windows
Source: Kim, Miryung, Thomas Zimmermann, and Nachiappan Nagappan. "An Empirical Study of RefactoringChallenges and Benefits at Microsoft."
IEEE Transactions on Software Engineering 7 (2014): 1-1.

21. Refactoring JDK

22. Tangles in
JDK

23. Copyright © 2015, Oracle and/or its affiliates. All rights reserved

24. Copyright © 2015, Oracle and/or its affiliates. All rights reserved

25. Copyright © 2015, Oracle and/or its affiliates. All rights reserved

26. Project Jigsaw in Java 9
Modularize JDK & JRE
Hide platform internal details such as sun.misc
Provide a module system for Java developers

27. Related work
"architectural bad smells"
"architecture smells"
"anti-patterns"
"architecturally-relevant code smells"
"contra-indicated patterns"
"architectural defects"
"[accidental] architectural anti-patterns"

28. Related work
"high-impact refactorings"
"architecture transformation"
"large refactorings"
"architecture-oriented refactorings"

29. Related work
• Catalog architecture smells or refactorings
• Architecture smell catalog by Garcia et al.
• Catalog of smells and refactoring by M. Stal (2007)
• Specific categories of architecture smells
• Ouni et al. “web service antipatterns" in the context
of Service Oriented Architectures
• Rama et al. discusses “modularity smells”

30. Related work
•Architecture refactoring case studies performed on
industrial projects
• Exploratory studies on emerging topics in architecture
refactoring
• Architecture refactoring in software product lines
• Architecture technical debt
• …

31. Potential Research
Directions
Catalog of architecture
smells and refactoring
Tool support
Economics of architecture
refactoring (quantifying
architecture technical debt)
Refactoring and emerging
architecture styles
and patterns

32. Example: Lack of tool
support
Unlike code refactoring, most
architectural refactoring is manual
due to lack of tool support!

33. Automated code smell
detection and refactoring

36. ganesh@codeops.tech @GSamarthyam
www.codeops.tech slideshare.net/sgganesh
+91 98801 64463 bit.ly/ganeshsg