Context The context-oriented programming paradigm is designed to enable self-adaptation, or dynamic behavior modification of software systems, in response to changes in their surrounding environment. Contextoriented programming offers an adaptation model, from a programming language perspective, that maintains a clean modularisation between the application and adaptation logic, as well as between the components providing adaptations. Objective We use three implementation techniques for context-oriented programming languages to assess their appropriateness to foster self-adaptive systems. These approaches take advantage of the capabilities offered by the host programming language to realize self-adaptation as proposed by context-oriented languages. Method We evaluate each of these approaches by assessing their modularity and complexity when defining adaptations, and by comparing their run-time performance on a simple benchmark. Results Our results show a higher modularity than that for common architecture based self-adaptive systems, while maintaining comparable performance. Conclusion We conclude that context-oriented programming is an appropriate paradigm to realize self-adaptation. Link to the paper: https://doi.org/10.1016/j.infsof.2021.106789

1. Nicolás Cardozo1 Kim Mens2
1Systems and Computing Engineering department - Universidad de los Andes, Bogotá - Colombia
2ICTEAM - UCLouvain, Louvain-la-Neuve - Belgium
kim.mens@uclouvain.be, n.cardozo@uniandes.edu.co
@ncardoz
Programming language
implementations for context-
oriented self-adaptive systems
INTERNATIONAL CONFERENCE ON PROGRAM COMPREHENSION

2. Journal of Information and Software Technology
Volume 143, March 2022
Nicolás Cardozo1 Kim Mens2
1Systems and Computing Engineering department - Universidad de los Andes, Bogotá - Colombia
2ICTEAM - UCLouvain, Louvain-la-Neuve - Belgium
kim.mens@uclouvain.be, n.cardozo@uniandes.edu.co
@ncardoz
Programming language
implementations for context-
oriented self-adaptive systems

3. 3
Adaptation
system behavior

4. 3
Adaptation
system behavior
context

5. 3
Adaptation
system behavior
context
self

6. 3
Adaptation
system behavior
context
self
internal
system
Adaptation

7. 3
Adaptation
system behavior
context
self
external
MAPE-K
system
Adaptor
Adaptation
internal
system
Adaptation

8. 4
External adaptation engines
Internal adaptation engines
• Inflexible
• Tightly couple with the system implementation
• Modular
• Customizable
• Reusable
Adaptation

9. 5
Internal adaptation engines
smart
open
resilient
extensible
highly-available
customizable
modular
fi
ne-grained
concise
understandable
Adaptation

10. 6
Context-oriented programming
@implementation Poi
NSString *name;
-(NSString*) name {
return [NSString stringWithFormat:@"INIT_ERROR-%@", @"name"];
}
@end

11. 6
Context-oriented programming
@implementation Poi
NSString *name;
-(NSString*) name {
NSString *query = [NSString stringWithFormat:@"SELECT name FROM Poi WITH
language = %@ AND id_poi = %d", @"en", [self poiId ]];
NSArray *res = [[NSArray alloc] initWithArray:[[self dbManager]
|loadDataFromDB:query]];
return [res objectAtIndex:0];
}
@end

12. 6
Context-oriented programming
@implementation Poi
NSString *name;
-(NSString*) name {
return [NSString stringWithFormat:@"INIT_ERROR-%@", @"name"];
}
@end

13. 7
Context-oriented programming
Contexts as first-class
entities of the system
Behavioral variations
as fine-grained
(partial) statements
isolated from the
system
activation and
deactivation
mechanisms to
compose and
withdraw system
behavior
@context English @contexts English
-(NSString*) name {
…
}
@activate(English)
@deactivate(English)

14. 8
Context-dependent method dispatch
(defmethod display-poi-info (poi)
(print “basic poi info”))
Use dispatch mechanisms to direct messages to the
appropriate implementation according to the context
Ambience - [Gonzalez et al. JUC 2008]

15. 8
Context-dependent method dispatch
Use dispatch mechanisms to direct messages to the
appropriate implementation according to the context
(with-context (@wifi)
)
(defmethod display-poi-info (poi)
(format t “~a n
Description: ~a ”
(name poi)
(detail-description poi))
Ambience - [Gonzalez et al. JUC 2008]

16. 8
Context-dependent method dispatch
Use dispatch mechanisms to direct messages to the
appropriate implementation according to the context
(with-context (@wifi)
)
(defgeneric display-poi-info (poi)
...)
Ambience - [Gonzalez et al. JUC 2008]

17. 8
Context-dependent method dispatch
Use dispatch mechanisms to direct messages to the
appropriate implementation according to the context
(with-context (@wifi)
)
(defmethod display-poi-info (poi)
(print “basic poi info”))
(defgeneric display-poi-info (poi)
...)
amos::send
Ambience - [Gonzalez et al. JUC 2008]

18. 8
Context-dependent method dispatch
Use dispatch mechanisms to direct messages to the
appropriate implementation according to the context
(with-context (@wifi)
)
(defmethod display-poi-info (@wifi poi)
(format t “~a n
Description: ~a”
(name poi)
(detail-description poi))
(defgeneric display-poi-info (poi)
...) amos::send
amos::prepend-slot
(activate @wifi)
Ambience - [Gonzalez et al. JUC 2008]

19. 9
Method replacement mechanisms
At the MOP level, switch method implementations between base
and adaptive behavior
void displayPOI (POI poi) {
NSString *res = @“%@ ”
NSLog(res, poi.description);
}
Subjective-C - [Gonzalez et al. SLE 2010]

20. 9
Method replacement mechanisms
At the MOP level, switch method implementations between base
and adaptive behavior
void displayPOI (POI poi) {
NSString *res = @“%@ ”
NSLog(res, poi.description);
}
displayPOI NSString *res = @“%@”
NSLog(res, poi.description);
SEL
IMP
Subjective-C - [Gonzalez et al. SLE 2010]

21. 9
Method replacement mechanisms
At the MOP level, switch method implementations between base
and adaptive behavior
void displayPOI (POI poi) {
NSString *res = @“%@ ”
NSLog(res, poi.description);
}
displayPOI
NSString *res = @“%@ n Description:
%@ ”
NSLog(res, poi.name,
poi.longDescription());
NSString *res = @“%@”
NSLog(res, poi.description);
@contexts Wifi
void displayPOI (POI poi) {
NSString *res = @“%@ n Description: %@ ”
NSLog(res, poi.name, poi.longDescription());
}
SEL
IMP
Subjective-C - [Gonzalez et al. SLE 2010]

22. 9
Method replacement mechanisms
At the MOP level, switch method implementations between base
and adaptive behavior
void displayPOI (POI poi) {
NSString *res = @“%@ ”
NSLog(res, poi.description);
}
displayPOI NSString *res = @“%@ n Description:
%@ ”
NSLog(res, poi.name,
poi.longDescription());
NSString *res = @“%@”
NSLog(res, poi.description);
@contexts Wifi
void displayPOI (POI poi) {
NSString *res = @“%@ n Description: %@ ”
NSLog(res, poi.name, poi.longDescription());
}
@activate(Wifi)
SEL
IMP
Subjective-C - [Gonzalez et al. SLE 2010]

23. 10
Fine-grained composition
Fine-grained module to be composed as appropriate for
specific situations
POI
- description
- displayPOI
- name
Context Traits - [Gonzalez et al. AOSD 2013]

24. 10
Fine-grained composition
Fine-grained module to be composed as appropriate for
specific situations
POI
- description
- displayPOI
- name
Wi
fi
<<trait>>
- description
- displayPOI
Wifi.activate()
Context Traits - [Gonzalez et al. AOSD 2013]

25. 10
Fine-grained composition
Fine-grained module to be composed as appropriate for
specific situations
POI
- description
- displayPOI
- name
Wi
fi
<<trait>>
- description
- displayPOI
+
POI
- description
- displayPOI
- name
=
Wifi.activate()
Context Traits - [Gonzalez et al. AOSD 2013]

26. 11
Evaluation
1. Expressiveness
2. Modularity
3. Performance of adaptation selection

27. 12
Modularity evaluation
Ambience
(LOC 793)
Common Lisp
(LOC 734)
Subjective-C
(LOC 3011)
Objective-C
(LOC 3265)
Context Traits
(LOC 1242)
ECMAScript
(LOC 1320)
0 25 50 75 100
17.73
3.14
6.95
4.22
23.84
10.97
29.62
35.91
19.69
17.48
54.22
50.32
52.65
60.95
73.35
78.31
21.93
38.71
Application Logic Adaptation Logic Adaptation Management

28. 12
Modularity evaluation
Ambience
(LOC 793)
Common Lisp
(LOC 734)
Subjective-C
(LOC 3011)
Objective-C
(LOC 3265)
Context Traits
(LOC 1242)
ECMAScript
(LOC 1320)
0 25 50 75 100
17.73
3.14
6.95
4.22
23.84
10.97
29.62
35.91
19.69
17.48
54.22
50.32
52.65
60.95
73.35
78.31
21.93
38.71
Application Logic Adaptation Logic Adaptation Management
Reduction in both the adaptation logic (~10%) and
(more substantially) its management (>40%)

29. 13
Performance evaluation
log
time
(in
milliseconds)
0.010
1.000
100.000
10000.000
1000000.000
Number of contexts
10 50 100 500 1000 2500 5000 10000
ifs
strategy
ambience
log
time
(in
milliseconds)
0.100
1.000
10.000
100.000
1000.000
Number of contexts
10 50 100 500 1000 2500 5000
ifs
strategy
context traits
log
time
(in
milliseconds)
0.0100000
1.0000000
100.0000000
10000.0000000
Number of contexts
10 50 100 500 1000 2500 5000 10000 25000 50000
ifs
strategy
subjective-c

30. 13
Performance evaluation
log
time
(in
milliseconds)
0.010
1.000
100.000
10000.000
1000000.000
Number of contexts
10 50 100 500 1000 2500 5000 10000
ifs
strategy
ambience
log
time
(in
milliseconds)
0.100
1.000
10.000
100.000
1000.000
Number of contexts
10 50 100 500 1000 2500 5000
ifs
strategy
context traits
log
time
(in
milliseconds)
0.0100000
1.0000000
100.0000000
10000.0000000
Number of contexts
10 50 100 500 1000 2500 5000 10000 25000 50000
ifs
strategy
subjective-c
Adaptation activations impact the use of adaptations,
upon message sends, or context changes

31. 14
Conclusion
External adaptation engines
Internal adaptation engines
• Modular
• Customizable
• Reusable
• Smart
• Open
• Resilient
• Extensible
• Highly-available
• Customizable
• Modular
• Fine-grained
• Concise
• Understandable

32. @FLAGlab in all media channels
Journal of Information and Software Technology
Volume 143, March 2022
Programming language
implementations for context-oriented
self-adaptive systems
Nicolás Cardozo1 Kim Mens2
1Systems and Computing Engineering department - Universidad de los Andes, Bogotá - Colombia
2ICTEAM - UCLouvain, Louvain-la-Neuve - Belgium
kim.mens@uclouvain.be, n.cardozo@uniandes.edu.co @ncardoz