Presentation at Euromicro SEAA 2022 Paper: https://doi.org/10.1109/SEAA56994.2022.00061

1. Christian Doppler Lab VaSiCS
LIT | Cyber-Physical Systems Lab
Johannes Kepler University Linz
Bad Smells in Industrial
Automation:
Sniffing out Feature Envy
Lisa Sonnleithner, Rick Rabiser, Alois Zoitl

2. Introduction and Background
© CDL VaSiCS, Lisa Sonnleithner, 2022 2
Certain suboptimal structures or
patterns in software
Bad Smells
Bad Smells lead to
Our goal
Maintenance issues, low software
quality, poor understandability, etc.
Identifying Feature Envy in
IEC 61499/Control Software

3. Feature Envy
3
© CDL VaSiCS, Lisa Sonnleithner, 2022

4. IEC 61499 – DSL for Distributed Control Systems
4
Composite Function Blocks
i := 0;
j := 0;
h := 0;
Asorted := sort(A);
Bsorted := sort(B);
REPEAT
X := Asorted[i];
Y := Bsorted[j];
IF X = Y THEN
results[h] := A;
results[h + 1] := Y;
h := h + 2;
i := i +1;
j := j+1;
ELSIF X < Y THEN
i := i + 1;
ELSE
j := j+1;
END_IF;
UNTIL i = 100 OR j = 100 END_REPEAT;
State Machine
Code
Network of Function Blocks
— Event Connections: Control Flow
— Data Connections: Information Flow
Atomic Function Blocks
© CDL VaSiCS, Lisa Sonnleithner, 2022

5. IEC 61499 – Example
5
© CDL VaSiCS, Lisa Sonnleithner, 2022

6. IEC 61499 – Example
6
SUB
PID
M RPM SP L
© CDL VaSiCS, Lisa Sonnleithner, 2022

7. Metric I:
Feature Envy Factor
K. Nongpong, “Feature envy factor: A metric for automatic feature envy detection,” in 2015 7th Int. Conf. on Knowledge and Smart Technology, 2015, pp. 7–12
7
𝐹𝐸𝐹 𝑜𝑏𝑗, 𝑚𝑡𝑑 =
𝑚
𝑛
𝑜𝑏𝑗 Composite FB
𝑚𝑡𝑑 FB inside a Composite FB
𝑚 nr. of connections from 𝑚𝑡𝑑 to 𝑜𝑏𝑗
𝑛 nr. of all connections of 𝑚𝑡𝑑
Can be calculated for Event and
Data Connections
© CDL VaSiCS, Lisa Sonnleithner, 2022

8. Metric I:
Feature Envy Factor
𝐹𝐸𝐹 𝑜𝑏𝑗, 𝑚𝑡𝑑 =
𝑚
𝑛
𝑜𝑏𝑗 Composite FB = MSpeedCtrl
𝑚𝑡𝑑 FB inside a Composite FB = PID
𝑚 nr. of connections from 𝑚𝑡𝑑 to 𝑜𝑏𝑗 = 2
𝑛 nr. of all connections of 𝑚𝑡𝑑 = 2
K. Nongpong, “Feature envy factor: A metric for automatic feature envy detection,” in 2015 7th Int. Conf. on Knowledge and Smart Technology, 2015, pp. 7–12
8
= 1
Ideal: High value for mtd to its obj
© CDL VaSiCS, Lisa Sonnleithner, 2022

9. Metric I:
Feature Envy Factor
𝐹𝐸𝐹 𝑜𝑏𝑗, 𝑚𝑡𝑑 =
𝑚
𝑛
𝑜𝑏𝑗 Composite FB = DataLogging
𝑚𝑡𝑑 FB inside a Composite FB = PID
𝑚 nr. of connections from 𝑚𝑡𝑑 to 𝑜𝑏𝑗 = 0
𝑛 nr. of all connections of 𝑚𝑡𝑑 = 2
K. Nongpong, “Feature envy factor: A metric for automatic feature envy detection,” in 2015 7th Int. Conf. on Knowledge and Smart Technology, 2015, pp. 7–12
9
= 0
Ideal: Low value for mtd to other obj
© CDL VaSiCS, Lisa Sonnleithner, 2022

10. Metric I:
Feature Envy Factor
𝐹𝐸𝐹 𝑜𝑏𝑗, 𝑚𝑡𝑑 =
𝑚
𝑛
𝑜𝑏𝑗 Composite FB
𝑚𝑡𝑑 FB inside a Composite FB
𝑚 nr. of connections from 𝑚𝑡𝑑 to 𝑜𝑏𝑗
𝑛 nr. of all connections of 𝑚𝑡𝑑
K. Nongpong, “Feature envy factor: A metric for automatic feature envy detection,” in 2015 7th Int. Conf. on Knowledge and Smart Technology, 2015, pp. 7–12
10
MSpeedCtrl DataLogging
CFlow DFlow CFlow DFlow
SUB 0.50 0.33 0.50 0.33
PID 1 1 0 0
M 0.50 1 0.50 0
RPM 0.67 0.50 0.33 0.50
SP 0 0 1 1
L 0 0 1 1
© CDL VaSiCS, Lisa Sonnleithner, 2022

11. Metric II:
Distance Measure
F. Simon, F. Steinbruckner, and C. Lewerentz, “Metrics based refactoring,” in Proceedings Fifth European Conf. on Software Maintenance and Reengineering, 2001, pp. 30–38
F. Simon, S. L ̈offler, and C. Lewerentz, “Distance based cohesion measuring,” 08 1999.
11
𝑑𝑖𝑠𝑡 𝐹𝐵1, 𝐹𝐵2 = 1 −
σ 𝐸𝑆
σ 𝐸𝐴
𝐹𝐵1 first FB
𝐹𝐵2 second FB
𝐸𝑆 sum of shared connections between 𝐹𝐵1 and 𝐹𝐵2
𝐸𝑆 sum of all connections of 𝐹𝐵1 and 𝐹𝐵2
Can be calculated for Event and
Data Connections
© CDL VaSiCS, Lisa Sonnleithner, 2022

12. Metric II:
Distance Measure
12
𝑑𝑖𝑠𝑡 𝐹𝐵1, 𝐹𝐵2 = 1 −
σ 𝐸𝑆
σ 𝐸𝐴
𝐹𝐵1 first FB
𝐹𝐵2 second FB
𝐸𝑆 sum of shared connections = 1
𝐸𝑆 sum of all connections = 3
= 0.67
F. Simon, F. Steinbruckner, and C. Lewerentz, “Metrics based refactoring,” in Proceedings Fifth European Conf. on Software Maintenance and Reengineering, 2001, pp. 30–38
F. Simon, S. L ̈offler, and C. Lewerentz, “Distance based cohesion measuring,” 08 1999.
Ideal: Low value for FBs in same CFB
© CDL VaSiCS, Lisa Sonnleithner, 2022

13. Metric II:
Distance Measure
13
𝑑𝑖𝑠𝑡 𝐹𝐵1, 𝐹𝐵2 = 1 −
σ 𝐸𝑆
σ 𝐸𝐴
𝐹𝐵1 first FB
𝐹𝐵2 second FB
𝐸𝑆 sum of shared connections
𝐸𝑆 sum of all connections
F. Simon, F. Steinbruckner, and C. Lewerentz, “Metrics based refactoring,” in Proceedings Fifth European Conf. on Software Maintenance and Reengineering, 2001, pp. 30–38
F. Simon, S. L ̈offler, and C. Lewerentz, “Distance based cohesion measuring,” 08 1999.
SUB PID M RPM SP L
SUB X 0.67 1 0.75 1 1
PID 0.67 X 0.67 1 1 1
M 1 0.67 X 0.75 1 1
RPM 0.75 1 0.75 X 0.75 1
SP 1 1 1 0.75 X 0.5
L 1 1 1 1 0.5 X
© CDL VaSiCS, Lisa Sonnleithner, 2022

14. Summary and Outlook
14
• Mapped Feature Envy Factor to IEC 61499
• Mapped Distance Measure to IEC 61499
• Performed first evaluation (example)
• Implementation
• Evaluation with real system
• Combine with automatic refactoring
Completed Next Steps
© CDL VaSiCS, Lisa Sonnleithner, 2022

15. Thank you!
Christian Doppler Lab VaSiCS
LIT | Cyber-Physical Systems Lab
Johannes Kepler University Linz
Univ.-Prof. Mag. Dr. Rick Rabiser | rick.rabiser@jku.at
DI Lisa Sonnleithner | lisa.sonnleithner@jku.at
Contact us!

16. Further Work
16
© CDL VaSiCS, Lisa Sonnleithner, 2022
Sonnleithner et al.:
Applying Visualization
Concepts to Large-Scale
Software Systems in Industrial
Automation.
VISSOFT 2022 (Oct 2/3)
Sonnleithner et al.:
Architectural Concepts for IEC
61499-based Machine Controls:
Beyond Normal Operation
Handling.
ETFA 2022 (next week)
Sonnleithner et al.:
Do you smell it too? Towards
Bad Smells in IEC 61499
Applications.
ETFA 2021
Sonnleithner et al.:
IEC 61499 Distributed Design
Patterns.
ETFA 2021