1. Alexander Serebrenik, Serguei Roubtsov LaQuSo & SET
Assessing Software Maintainability with Visual Analytics: SQuAVisiT Experience
Alexander Serebrenik, Serguei Roubtsov
LaQuSo & SET

2. Real life industrial systems
They are often:
Not only OO (e.g., legacy systems)
Heterogeneous (C/Assembler, Cobol/PL SQL,…)
Incomplete (some code is in libraries and third-party components)
Not compilable and executable within analysis environment ( ‘weird’ OS, proprietary development environment, …)
/ LaQuSo / Mathematics & Computer Science

3. Goal: Maintainability assessment
Maintenance is a problem
2007, US companies spent 100 billion US$
In some Dutch companies: 60-80% of the budget
/ LaQuSo / Mathematics & Computer Science

4. What code is hard to maintain?
Badly understandable
not documented
cluttered or inconsistently used/developed code
too big
Badly modifiable
code is duplicated
code is intertwined
code is non-extendable
code is non-portable
Badly testable / analysable
code is too complex
/ LaQuSo / Mathematics & Computer Science

5. Approaches Typical approaches Problems with Analyze + Visualize
“Pretty pictures”: do not convey meaning
“Ugly pictures”: do not scale
“One to rule them all”: rigid architectures
Different tools provide different insights!
/ LaQuSo / Mathematics & Computer Science

6. Visual Software Analytics = Analysis + Visualisation + Flexibility
Our approach
Visual Software Analytics =
Analysis + Visualisation + Flexibility AV
Repository
(2)
(3)
(4)
(1)
Name, Class Count, Abstract Class Count, Ca, Ce, A, I, D, V:
com.caucho.burlap.client,0,0,1,0,0,0,1,1
com.caucho.burlap.io,0,0,1,0,0,0,1,1
bsh,0,0,1,0,0,0,1,1
com.ibatis.common.util,0,0,1,0,0,0,1,1
oracle.toplink.exceptions,0,0,2,0,0,0,1,1
oracle.toplink.essentials.sessions,0,0,1,0,0,0,1,1
com.caucho.hessian.server,0,0,1,0,0,0,1,1
com.caucho.hessian.io,0,0,1,0,0,0,1,1
com.caucho.burlap.server,0,0,1,0,0,0,1,1
com.caucho.hessian.client,0,0,1,0,0,0,1,1
oracle.toplink.internal.databaseaccess,0,0,1,0,0,0,1,1
oracle.toplink.expressions,0,0,1,0,0,0,1,1
oracle.toplink.sessionbroker,0,0,1,0,0,0,1,1
oracle.toplink.sessions,0,0,2,0,0,0,1,1
oracle.toplink.threetier,0,0,1,0,0,0,1,1
oracle.toplink.queryframework,0,0,1,0,0,0,1,1
oracle.toplink.jndi,0,0,1,0,0,0,1,1
oracle.toplink.logging,0,0,1,0,0,0,1,1
oracle.toplink.publicinterface,0,0,2,0,0,0,1,1
oracle.toplink.tools.sessionconfiguration,0,0,1,0,0,0,1,1
org.apache.catalina.loader,0,0,1,0,0,0,1,1
org.aspectj.weaver,0,0,2,0,0,0,1,1
org.aspectj.weaver.ast,0,0,1,0,0,0,1,1
org.apache.axis.encoding.ser,0,0,1,0,0,0,1,1
org.aopalliance.intercept,0,0,24,0,0,0,1,1
oracle.toplink.tools.sessionmanagement,0,0,1,0,0,0,1,1
org.aopalliance.aop,0,0,9,0,0,0,1,1
org.quartz.spi,0,0,1,0,0,0,1,1
org.aspectj.weaver.loadtime,0,0,1,0,0,0,1,1
org.aspectj.weaver.bcel,0,0,1,0,0,0,1,1
org.aspectj.weaver.internal.tools,0,0,1,0,0,0,1,1
org.quartz.utils,0,0,1,0,0,0,1,1
org.springframework.aop,24,20,17,6,0,83,0,26,0,09,1
org.quartz.xml,0,0,1,0,0,0,1,1
org.springframework.jdbc.core,53,20,6,20,0,38,0,77,0,15,1
org.springframework.jdbc.core.metadata,22,2,1,10,0,09,0,91,0,1
org.springframework.aop.config,17,3,1,15,0,18,0,94,0,11,1
org.springframework.aop.framework,37,9,22,18,0,24,0,45,0,31,1
org.springframework.aop.aspectj,39,7,3,24,0,18,0,89,0,07,1
org.springframework.aop.aspectj.annotation,27,3,0,19,0,11,1,0,11,1
org.springframework.aop.aspectj.autoproxy,3,0,1,8,0,0,89,0,11,1
org.springframework.jdbc.object,14,8,0,12,0,57,1,0,57,1
org.springframework.jdbc.support.incrementer,15,4,0,8,0,27,1,0,27,1
org.springframework.jdbc.datasource.lookup,8,2,2,13,0,25,0,87,0,12,1
org.springframework.jdbc.support,15,5,12,16,0,33,0,57,0,1,1
org.springframework.jdbc.datasource,27,7,13,14,0,26,0,52,0,22,1
org.springframework.jdbc.core.support,8,5,2,14,0,62,0,88,0,5,1
org.springframework.jdbc.core.namedparam,10,4,3,12,0,4,0,8,0,2,1
org.springframework.jdbc.core.simple,17,6,0,12,0,35,1,0,35,1
org.springframework.web.servlet.view.xslt,4,2,0,17,0,5,1,0,5,1
org.springframework.web.struts,16,5,0,22,0,31,1,0,31,1
org.springframework.jdbc.support.xml,7,6,0,7,0,86,1,0,86,1
org.springframework.jdbc.support.rowset,4,2,2,6,0,5,0,75,0,25,1
org.springframework.jdbc.support.nativejdbc,10,2,2,7,0,2,0,78,0,02,1
org.springframework.jdbc.support.lob,18,5,5,12,0,28,0,71,0,02,1
org.xml.sax,0,0,3,0,0,0,1,1
org.springframework.web.util,24,6,26,15,0,25,0,37,0,38,1
org.w3c.dom,0,0,12,0,0,0,1,1
/ LaQuSo / Mathematics & Computer Science

7. SQuAVisiT Flexible Languages Analysis tools Visualization tools
Plug-in architecture
Languages
C, Cobol, Java, JavaScript, PL/SQL
Analysis tools
dependency extractors, duplication detectors, error detectors, metrics calculators, parsers, style checkers
Visualization tools
Gemini, GraphViz, ExTraVis (thank you Danny!), MatrixZoom, MetricsView
/ LaQuSo / Mathematics & Computer Science

8. 1000 facets of visual analytics based on LaQuSo case studies
/ LaQuSo / Mathematics & Computer Science

9. LaQuSo?
/ LaQuSo / Mathematics & Computer Science

10. Industrial cases Usually up to 2 weeks analysis time
Range from 150 KLOC to 1.7 MLOC
Homogeneous and heterogeneous
Customers usually report problems experienced:
Need to migrate due to discontinuation of support by a third party
Danger of architecture deterioration due to extensive change
Lack of knowledge due to high degree of staff rotation
Maintenance (dis)continuation decision
As an illustration we discuss only some of the analyses carried out in each case.
/ LaQuSo / Mathematics & Computer Science

11. Overview of industrial cases
Expert system
Emb. system
Front-end
Pension fund
Size (KLOC)
300 (JavaScript, C++, Java, PL SQL, Cobol)
150
(C)
700
(Java, J2EE platform)
1700
(Cobol, PL SQL)
Age (years) 15 6
Not yet in use 17
Analyses shown
Dependencies, duplication
Dependencies
OO metrics
Dead code
Visualization
/ LaQuSo / Mathematics & Computer Science

12. Industrial case: Insurance company’s expert system
What kind of system do we have?
Heterogeneous: Javascript, PL/SQL, C++, Java, Cobol
Medium size: 300 KLOC
15 years old
Scarce documentation
Oracle DB
Problem reported
Maintenance (dis)continuation decision
Expert system
/ LaQuSo / Mathematics & Computer Science

13. Dependencies Model: Matrix View
Data layer
(Almost) layered: good design
BUT data layer is accessed from several layers
Layers affected by calls from top layer are visible (red squares)
What are the maintenance implications of this figure?
Do not support the green parts!
/ LaQuSo / Mathematics & Computer Science

14. Dependencies Model: Extravis
Absence of dedicated data access layer is confirmed
HTTP is called only internally
Green ‘bubbles’: controversial coding approach
Parameters as names f(1,3) -> f_1_3
/ LaQuSo / Mathematics & Computer Science

15. Code duplication model: CCFinder/Gemini
PL/SQL part
Code is polluted with duplication: restructuring would improve maintainability but may change the architecture
PL/SQL
Upper corner: tlp00000 and variants
Next tlp0040 (diacritics elimination conversions)
Next tlp21200 vs tlp61200
Next tlp21400 and variants (central group)
/ LaQuSo / Mathematics & Computer Science

16. What can we conclude? Layered architecture
System is well-structured
Controversial coding practices
But locally well-documented (not shown here)
Code polluted by duplication
Low impact if no major changes are expected
Conclusions:
Maintain for limited amount of time (3-5 years)
Encourage knowledge sharing
Develop overview documentation
/ LaQuSo / Mathematics & Computer Science

17. Assessment required multiple analyses and visualizations:
Case conclusions
Assessment required multiple analyses and visualizations:
Dependencies
Code duplication
and in fact even more
Different techniques provide different insights!
/ LaQuSo / Mathematics & Computer Science

18. Industrial case: Embedded System
What kind of code do we have?
C with embedded Assembler
Complete
Modules of interest can be parsed
Medium size: 150 KLOC
No documentation
Problems reported
Danger of architecture deterioration due to extensive change.
Developer’s assumption
Layered architecture
/ LaQuSo / Mathematics & Computer Science

19. Dependencies Structure
system is poorly layered
unexpected cross-dependencies exist between components
/ LaQuSo / Mathematics & Computer Science

20. What kind of system do we have?
Industrial case: Insurance company’s front-end
What kind of system do we have?
Technical data
Homogeneous: Java
Large: 750 KLOC
Oracle DB
J2EE (Spring Framework)
Recently developed by a third party
No documentation
Code was not available for our inspection (black box)
Expert system
/ LaQuSo / Mathematics & Computer Science

21. Code not available? What can we do?
Customer
SQuAVisiT
Install locally.
Perform measurements.
Tune
results
Analyse, interpret.
report
/ LaQuSo / Mathematics & Computer Science

22. Understandability: Documentation
No technical documentation available.
Comments percentage
Average: 43%
Ranging from 0% to 1500%. Why?
large repeated header blocks of comments
commented out code
Javadoc
85260 violations
Missing or malformed declarations
Documentation generation is impossible, or
Documentation quality is compromised
Documentation quality should be reassessed!
/ LaQuSo / Mathematics & Computer Science

23. Object-Oriented Metrics for Packages
Abstractness of a package P: ease of inheritance
A = #abstract classes in P/#classes in P
Instability of a package P: ease of change
I = Ce/(Ce + Ca)
Efferent coupling (Ce)
#packages P depends upon
Afferent coupling (Ca)
#packages dependent upon P
/ LaQuSo / Mathematics & Computer Science

24. Modification: Abstractness and Instability
Imbalance is
significant
Implementation classes
Zone of uselessness: lack of dependencies on them 1
Instability (I)
Interface classes
Zone of pain: hard to change 1
Abstractness (A)
/ LaQuSo / Mathematics & Computer Science

25. Modification: Abstractness and Instability
Normalized distance = |Abstractness – Instability + 1|
Purple – the application, yellow – Spring
The application is better!
/ LaQuSo / Mathematics & Computer Science

26. Object-Oriented Metrics for Classes
WMC – here: number of methods per class
DIT – depth of inheritance tree
NOC – number of children
CBO – number of classes related to a given class
RFC – number of different methods that can be executed when a method of the class is invoked
/ LaQuSo / Mathematics & Computer Science

27. Closer look: Depth of Inheritance
50%of classes with inheritance depth 0.
Lack of reuse via inheritance.
/ LaQuSo / Mathematics & Computer Science

28. Closer look: coupling between objects
CBO = Average #classes related to the given
NASA High Quality
NASA Low Quality
Spring Framework
Loan Path
1.25
2.48
4.45
6.83
Average coupling is too high!
Reduce dependencies
/ LaQuSo / Mathematics & Computer Science

29. What have we seen? Understandable not documented Modification
No documentation. Poor Javadoc. Commented out code suspected.
Modification
intertwined
Coupling between objects
abstractness instability
Better than Spring but improvement possible.
inheritance
DIT low. Lack of reuse.
Architecture is suboptimal
Documentation should be reassessed
/ LaQuSo / Mathematics & Computer Science

30. Recall: we have not seen the code!
Case conclusions
Recall: we have not seen the code!
Black box analysis
Metrics provide valuable insights in software quality
Assessment results were confirmed by the customer
/ LaQuSo / Mathematics & Computer Science

31. Industrial case: Pension fund
What kind of system do we have?
Homogeneous: Cobol
Large: 1.7 MLOC
17 years old
Oracle DB
Problem reported
Need to migrate due to discontinuation of support
/ LaQuSo / Mathematics & Computer Science

32. “Empty spaces” in the visualization
Dead code?
“Empty spaces” in the visualization
1216 modules not called by other modules
Dead code?
Other (sub)systems?
~600 are dead
Confirmed by the developers
/ LaQuSo / Mathematics & Computer Science

33. Conclusions
Visual software analytics = assessment supported by visualization, analysis and tool flexibility
SQuAVisiT is a flexible tool allowing
To analyse different languages
To address different maintainability aspects
To combine different analysis and visualization techniques
In practice, SQuAVisiT supported analysis of
Middle-size to large systems (150 KLOC – 1.7 MLOC)
Short amount of time: days
Even black box!
/ LaQuSo / Mathematics & Computer Science