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Subjective-C: Bringing Context to Mobile Platform Programming

kim.mens
kim.mens

The document details the 3rd International Conference on Software Language Engineering, focusing on the Subjective-C programming language which emphasizes context-aware mobile platform programming. It discusses the importance of shifting programming mindsets from isolation to context, as well as presenting conditional statement examples and software architectures in programming. Additionally, it outlines a language engineering approach that features subjective programming and context management through multiple dispatch prototypes.

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3rd International Conference on Software Language Engineering Subjective-C Bringing Context to Mobile Platform Programming ICTEAM / UCLouvain / Belgium Sebastián González Alfredo Cádiz Nicolás Cardozo Jean-Christophe Libbrecht Kim Mens Julien Goffaux 13 October 2010 Thursday 21 October 2010
3rd International Conference on Software Language Engineering Subjective-C Bringing Context to Mobile Platform Programming ICTEAM / UCLouvain / Belgium Sebastián González Sebastián González Alfredo Cádiz Nicolás Cardozo Jean-Christophe Libbrecht Kim Mens Kim Mens Julien Goffaux 13 October 2010 Thursday 21 October 2010
3rd International Conference on Software Language Engineering Subjective-C Bringing Context to Mobile Platform Programming ICTEAM / UCLouvain / Belgium Sebastián González Sebastián González Alfredo Cádiz Nicolás Cardozo Jean-Christophe Libbrecht Kim Mens Kim Mens Julien Goffaux 13 October 2010 Thursday 21 October 2010
Research Context 2 Thursday 21 October 2010
Research Goal Programming Mindset Towards a Mindset Shift programming in isolation programming in context ? ? ? ? ? ? 3 Thursday 21 October 2010
Contemporary Solution conditional statements class phone { method receive ( call ) { if ( phone.isOffHook( ) ) play( phone.callWaitingSignal( ), 2 ); else if ( phone.environment( ).acoustics( ).isQuiet( ) ) phone.vibrate( 5 ); else if ( phone.user( ).isUnavailable( ) ) forwardCall( call, phone.forwardNumber( ) ); else play( phone.ringTone( ), 10 ); } 4 Thursday 21 October 2010
Contemporary Solution conditional statements class phone { method receive ( call ) { if ( phone.isOffHook( ) ) play( phone.callWaitingSignal( ), 2 ); else if ( phone.environment( ).acoustics( ).isQuiet( ) ) phone.vibrate( 5 ); else if ( phone.user( ).isUnavailable( ) ) forwardCall( call, phone.forwardNumber( ) ); else play( phone.ringTone( ), 10 ); } 4 Thursday 21 October 2010
Contemporary Solution conditional statements class phone { method receive ( call ) { if ( phone.isOffHook( ) ) play( phone.callWaitingSignal( ), 2 ); else if ( phone.environment( ).acoustics( ).isQuiet( ) ) phone.vibrate( 5 ); · else if ( phone.user( ).isUnavailable( ) ) forwardCall( call, phone.forwardNumber( ) ); else play( phone.ringTone( ), 10 ); } 4 Thursday 21 October 2010
Contemporary Solution conditional statements class phone { method receive ( call ) { if ( phone.isOffHook( ) ) play( phone.callWaitingSignal( ), 2 ); else if ( phone.environment( ).acoustics( ).isQuiet( ) ) phone.vibrate( 5 ); · else if ( phone.user( ).isUnavailable( ) ) forwardCall( call, phone.forwardNumber( ) ); else play( phone.ringTone( ), 10 ); } 4 Thursday 21 October 2010
Contemporary Solution conditional statements class phone { method receive ( call ) { if ( phone.isOffHook( ) ) play( phone.callWaitingSignal( ), 2 ); else if ( phone.environment( ).acoustics( ).isQuiet( ) ) phone.vibrate( 5 ); · else if ( phone.user( ).isUnavailable( ) ) forwardCall( call, phone.forwardNumber( ) ); else play( phone.ringTone( ), 10 ); ∅ } 4 Thursday 21 October 2010
Contemporary Solution conditional statements class phone { method receive ( call ) { if ( phone.isOffHook( ) ) play( phone.callWaitingSignal( ), 2 ); else if ( phone.environment( ).acoustics( ).isQuiet( ) ) phone.vibrate( 5 ); · else if ( phone.user( ).isUnavailable( ) ) forwardCall( call, phone.forwardNumber( ) ); else play( phone.ringTone( ), 10 ); ∅ } Tangled Scattered Fixed 4 Thursday 21 October 2010
Contemporary Solution special software architectures class Phone { attribute strategy; method receive ( call ) { strategy.receive ( call ); } } 5 Thursday 21 October 2010
Contemporary Solution special software architectures class DefaultStrategy { method receive ( call ) { ... } } class QuietStrategy class Phone { method receive ( call ) { ... } } · { attribute strategy; method receive ( call ) class OffHookStrategy { strategy.receive ( call ); } } { method receive ( call ) { ... } } class UnavailableStrategy { method receive ( call ) { ... } } 5 Thursday 21 October 2010
Contemporary Solution special software architectures class DefaultStrategy { method receive ( call ) { ... } } class QuietStrategy class Phone { method receive ( call ) { ... } } · { attribute strategy; method receive ( call ) class OffHookStrategy { strategy.receive ( call ); } } { method receive ( call ) { ... } } class UnavailableStrategy { method receive ( call ) { ... } } 5 Thursday 21 October 2010
Contemporary Solution special software architectures class DefaultStrategy { method receive ( call ) { ... } } class QuietStrategy class Phone { method receive ( call ) { ... } } { attribute strategy; method receive ( call ) class OffHookStrategy { strategy.receive ( call ); } } { method receive ( call ) { ... } } class UnavailableStrategy { method receive ( call ) { ... } } Infrastructural burden Fixed adaptation points 5 Thursday 21 October 2010
Solution Language engineering approach 6 Thursday 21 October 2010
Solution Language engineering approach Multiple dispatch Prototypes PMD CLOS Self Smalltalk 6 Thursday 21 October 2010
Solution Language engineering approach Subjective Programming Multiple dispatch Prototypes PMD CLOS Self Smalltalk 6 Thursday 21 October 2010
Solution Language engineering approach Context Management Subjective Programming Multiple dispatch Prototypes PMD CLOS Self Smalltalk 6 Thursday 21 October 2010
Solution Language engineering approach Context-Oriented Programming Context Management Subjective Programming Multiple dispatch Prototypes PMD CLOS Self Smalltalk 6 Thursday 21 October 2010
Solution Language engineering approach Ambience [DLS’07] Context-Oriented Programming Context Management Subjective Programming Multiple dispatch Prototypes PMD CLOS Self Smalltalk 6 Thursday 21 October 2010
Solution Language engineering approach Ambience [DLS’07] Context-Oriented Programming Context Management Subjective Programming Multiple dispatch Prototypes PMD CLOS Self Smalltalk 6 Thursday 21 October 2010
Solution Language engineering approach Ambience [DLS’07] Context-Oriented Programming Context Management Subjective Programming Multiple dispatch Single dispatch Prototypes Open Classes PMD Objective-C CLOS C Self Smalltalk 6 Thursday 21 October 2010
Solution Language engineering approach Ambience [DLS’07] Context-Oriented Programming Context Management Subjective Programming Subjective Programming Multiple dispatch Single dispatch Prototypes Open Classes PMD Objective-C CLOS C Self Smalltalk 6 Thursday 21 October 2010
Solution Language engineering approach Ambience [DLS’07] Context-Oriented Programming Context Management Context Management Subjective Programming Subjective Programming Multiple dispatch Single dispatch Prototypes Open Classes PMD Objective-C CLOS C Self Smalltalk 6 Thursday 21 October 2010
Solution Language engineering approach Ambience [DLS’07] Context-Oriented Programming Context-Oriented Programming Context Management Context Management Subjective Programming Subjective Programming Multiple dispatch Single dispatch Prototypes Open Classes PMD Objective-C CLOS C Self Smalltalk 6 Thursday 21 October 2010
Solution Language engineering approach Ambience [DLS’07] Subjective-C Context-Oriented Programming Context-Oriented Programming Context Management Context Management Subjective Programming Subjective Programming Multiple dispatch Single dispatch Prototypes Open Classes PMD Objective-C CLOS C Self Smalltalk 6 Thursday 21 October 2010
Solution Language engineering approach Ambience [DLS’07] Subjective-C Context-Oriented Programming Context-Oriented Programming Context Management Context Management Subjective Programming Subjective Programming Multiple dispatch Single dispatch Prototypes Open Classes PMD Objective-C CLOS C Self Smalltalk 6 Thursday 21 October 2010
Subjective-C 1 General mindset 2 Context definition 3 Context-specific behaviour 4 Context relations 5 Implementation 6 Efficiency 7 Thursday 21 October 2010
1 Mindset 2 Context 3 Behaviour 4 Relations 5 Implementation 6 Efficiency Context-Aware System Architecture World Sensors Actuators Subjective-C Context Application Discovery Behaviour external internal context effect context information arbitrated context Context changes Active Management Context 8 Thursday 21 October 2010
1 Mindset 2 Context 3 Behaviour 4 Relations 5 Implementation 6 Efficiency What is context? Computationally Well-defined situation accessible information (Contexts) Z axis = 0.03 Landscape orientation Battery charge = 220 mAh Low battery charge Idle cycles = 11 MHz High CPU load Location = 51°26′N 5°29′E Eindhoven no semantics action can be taken situations can be reified 9 Thursday 21 October 2010
1 Mindset 2 Context 3 Behaviour 4 Relations 5 Implementation 6 Efficiency Case Study 10 Thursday 21 October 2010
1 Mindset 2 Context 3 Behaviour 4 Relations 5 Implementation 6 Efficiency Case Study UILabel class drawTextInRect: Draws the receiver’s text in the specified rectangle. - (void)drawTextInRect:(CGRect)rect Parameters rect The rectangle in which to draw the text. Discussion You should not call this method directly. This method should only be overridden by subclasses that want to modify the default drawing behavior for the label’s text. Availability Available in iOS 2.0 and later. Declared In UILabel.h 11 Thursday 21 October 2010
1 Mindset 2 Context 3 Behaviour 4 Relations 5 Implementation 6 Efficiency Case Study UILabel class drawTextInRect: Draws the receiver’s text in the specified rectangle. - (void)drawTextInRect:(CGRect)rect Parameters rect The rectangle in which to draw the text. Discussion You should not call this method directly. This method should only be overridden by subclasses that want to modify the default drawing behavior for the label’s text. Availability Available in iOS 2.0 and later. Declared In UILabel.h 11 Thursday 21 October 2010
1 Mindset 2 Context 3 Behaviour 4 Relations 5 Implementation 6 Efficiency Subjective-C: Look & Feel @implementation UILabel (color) #context Landscape - (void)drawTextInRect:(CGRect)rect { self.textColor = [UIColor greenColor]; [superContext drawTextInRect:rect]; } @end 12 Thursday 21 October 2010
1 Mindset 2 Context 3 Behaviour 4 Relations 5 Implementation 6 Efficiency Subjective-C: Look & Feel Open classes @implementation UILabel (color) Objective-C #context Landscape - (void)drawTextInRect:(CGRect)rect { self.textColor = [UIColor greenColor]; [superContext drawTextInRect:rect]; } @end 12 Thursday 21 October 2010
1 Mindset 2 Context 3 Behaviour 4 Relations 5 Implementation 6 Efficiency Subjective-C: Look & Feel Open classes @implementation UILabel (color) Objective-C COP #context Landscape Subjective-C - (void)drawTextInRect:(CGRect)rect { self.textColor = [UIColor greenColor]; [superContext drawTextInRect:rect]; } @end 12 Thursday 21 October 2010
1 Mindset 2 Context 3 Behaviour 4 Relations 5 Implementation 6 Efficiency Subjective-C: Look & Feel Open classes @implementation UILabel (color) Objective-C COP #context Landscape Subjective-C - (void)drawTextInRect:(CGRect)rect { self.textColor = [UIColor greenColor]; [superContext drawTextInRect:rect]; } @end ✓ Adaptation of any existing component ✓ No access to original source code needed ✓ Adaptations can be cleanly modularised 12 Thursday 21 October 2010
1 Mindset 2 Context 3 Behaviour 4 Relations 5 Implementation 6 Efficiency Context Relations Strong Inclusion Eindhoven Netherlands Weak Inclusion Museum Quiet Requirement HDVideo BatteryHigh Exclusion Landscape Portrait 13 Thursday 21 October 2010
1 Mindset 2 Context 3 Behaviour 4 Relations 5 Implementation 6 Efficiency Programmatic Context Definition // Create contexts Context* Room = [[Context alloc] initWithName:@"Room"]; Context* Bedroom = [[Context alloc] initWithName:@"Bedroom"]; Context* Day = [[Context alloc] initWithName:@"Day"]; Context* Night = [[Context alloc] initWithName:@"Night"]; ... // Register contexts [CONTEXT addContext:Room]; [CONTEXT addContext:Bedroom]; [CONTEXT addContext:Day]; [CONTEXT addContext:Night]; ... // Establish context relations [Day addExclusionRelationWith:Night]; [Bedroom addHardInclusionRelationWith:Room]; ... 14 Thursday 21 October 2010
1 Mindset 2 Context 3 Behaviour 4 Relations 5 Implementation 6 Efficiency Context Declaration Language Contexts: Relations: // Create contexts Context* Room = [[Context alloc] initWithName:@"Room"]; Context* Bedroom = [[Context alloc] initWithName:@"Bedroom"]; >< Night Room Day Context* Livingroom Day = [[Context alloc] initWithName:@"Day"]; Sun >< Rain Context* Kitchen Night = [[Context alloc] initWithName:@"Night"]; ... Bedroom Livingroom -> TV Bathroom Livingroom -> Window // Register contexts Day Livingroom -> Luminosity [CONTEXT addContext:Room]; [CONTEXT addContext:Bedroom]; Night Livingroom -> Temperature [CONTEXT addContext:Day]; Kitchen -> Luminosity [CONTEXT addContext:Night]; TV Bedroom -> Temperature ... Window Bedroom -> Luminosity Temperature Bedroom -> Window // Establish context relations Luminosity Bathroom -> Temperature [Day addExclusionRelationWith:Night]; [Bedroom addHardInclusionRelationWith:Room]; Bathroom -> Luminosity ... Sun Rain Bathroom => Room Electricity Kitchen => Room Livingroom => Room Bedroom => Room TV =< Electricity Luminosity =< Electricity Window =< Sun 14 Thursday 21 October 2010
1 Mindset 2 Context 3 Behaviour 4 Relations 5 Implementation 6 Efficiency Context Declaration Language // Create contexts Context* Room = [[Context alloc] initWithName:@"Room"]; Context* Bedroom = [[Context alloc] initWithName:@"Bedroom"]; Context* Day = [[Context alloc] initWithName:@"Day"]; Context* Night = [[Context alloc] initWithName:@"Night"]; ... // Register contexts [CONTEXT addContext:Room]; [CONTEXT addContext:Bedroom]; [CONTEXT addContext:Day]; [CONTEXT addContext:Night]; ... // Establish context relations [Day addExclusionRelationWith:Night]; [Bedroom addHardInclusionRelationWith:Room]; ... 14 Thursday 21 October 2010
1 Mindset 2 Context 3 Behaviour 4 Relations 5 Implementation 6 Efficiency Other Generated Code // Create contexts Context* Room = [[Context alloc] initWithName:@"Room"]; Context* Bedroom = [[Context alloc] initWithName:@"Bedroom"]; Context* Day = [[Context alloc] initWithName:@"Day"]; Context* Night = [[Context alloc] initWithName:@"Night"]; ... // Register contexts [CONTEXT addContext:Room]; [CONTEXT addContext:Bedroom]; [CONTEXT addContext:Day]; [CONTEXT addContext:Night]; ... // Establish context relations #context Bedroom [Day addExclusionRelationWith:Night]; -(Context*) getActiveRoom{ [Bedroom addHardInclusionRelationWith:Room]; ! return [CONTEXT getContext:@"Bedroom"]; ... } // Register context-specific methods [MANAGER addMethod:@selector(Context_Bedroom_getActiveRoom) forClass:[DomoticsServerViewController class] forContextNames:[[NSSet alloc] initWithObjects:@"Bedroom" ,nil] withDefautSel:@selector(getActiveRoom) withPriority:0]; ... 14 Thursday 21 October 2010
1 Mindset 2 Context 3 Behaviour 4 Relations 5 Implementation 6 Efficiency Other Generated Code // Create contexts Context* Room = [[Context alloc] initWithName:@"Room"]; Context* Bedroom = [[Context alloc] initWithName:@"Bedroom"]; Context* Day = [[Context alloc] initWithName:@"Day"]; Context* Night = [[Context alloc] initWithName:@"Night"]; ... // Register contexts [CONTEXT addContext:Room]; [CONTEXT addContext:Bedroom]; [CONTEXT addContext:Day]; [CONTEXT addContext:Night]; ... // Establish context relations [Day addExclusionRelationWith:Night]; [Bedroom addHardInclusionRelationWith:Room]; ... // Register context-specific methods [MANAGER addMethod:@selector(Context_Bedroom_getActiveRoom) forClass:[DomoticsServerViewController class] forContextNames:[[NSSet alloc] initWithObjects:@"Bedroom" ,nil] withDefautSel:@selector(getActiveRoom) withPriority:0]; ... 14 Thursday 21 October 2010
1 Mindset 2 Context 3 Behaviour 4 Relations 5 Implementation 6 Efficiency Application Contexts @implementation LowpassFilter -(void)addAcceleration:(UIAcceleration*)accel { ! double alpha = filterConstant; ! ! if(adaptive) ! ! alpha = ... // big formula to calculate the alpha level ! ! x = accel.x * alpha + x * (1.0 - alpha); ! y = accel.y * alpha + y * (1.0 - alpha); ! z = accel.z * alpha + z * (1.0 - alpha); } -(NSString*)name { ! return adaptive ? @"Adaptive Lowpass Filter" : @"Lowpass Filter"; } ... 15 Thursday 21 October 2010
1 Mindset 2 Context 3 Behaviour 4 Relations 5 Implementation 6 Efficiency Application Contexts @implementation LowpassFilter #context LowPassFilter -(void)addAcceleration:(UIAcceleration*)accel { ! double alpha = [self getAlpha:accel]; ! ! x = accel.x * alpha + x * (1.0 - alpha); ! y = accel.y * alpha + y * (1.0 - alpha); ! z = accel.z * alpha + z * (1.0 - alpha); } #context !Adaptive -(double) getAlpha:(UIAcceleration*)accel{ ! return filterConstant; } #context LowPassFilter Adaptive -(double) getAlpha:(UIAcceleration*)accel { ! return // big formula to calculate the alpha level; } 16 Thursday 21 October 2010
1 Mindset 2 Context 3 Behaviour 4 Relations 5 Implementation 6 Efficiency Application Contexts @implementation LowpassFilter Contexts: #context LowPassFilter Adaptive -(void)addAcceleration:(UIAcceleration*)accel Paused { LowPassFilter ! double alpha = [self getAlpha:accel]; HighPassFilter ! ! x = accel.x * alpha + x * (1.0 - alpha); Filter ! y = accel.y * alpha + y * (1.0 - alpha); Relations: ! z = accel.z * alpha + z * (1.0 - alpha); } LowPassFilter >< HighPassFilter LowPassFilter => Filter #context !Adaptive HighPassFilter => Filter -(double) getAlpha:(UIAcceleration*)accel{ ! return filterConstant; } #context LowPassFilter Adaptive -(double) getAlpha:(UIAcceleration*)accel { ! return // big formula to calculate the alpha level; } 16 Thursday 21 October 2010
1 Mindset 2 Context 3 Behaviour 4 Relations 5 Implementation 6 Efficiency Implementation dynamic method pre-dispatch UILabel @property NSString *text @property UIFont *font ... Portrait impl - (void)Portrait_drawTextInRect:(CGRect)rect - (void)Landscape_drawTextInRect:(CGRect)rect Landscape impl - (void)Default_drawTextInRect:(CGRect)rect - (void)drawTextInRect:(CGRect)rect Default impl 17 Thursday 21 October 2010
1 Mindset 2 Context 3 Behaviour 4 Relations 5 Implementation 6 Efficiency Implementation dynamic method pre-dispatch UILabel @property NSString *text @property UIFont *font ... vtable Portrait impl - (void)Portrait_drawTextInRect:(CGRect)rect - (void)Landscape_drawTextInRect:(CGRect)rect Landscape impl - (void)Default_drawTextInRect:(CGRect)rect - (void)drawTextInRect:(CGRect)rect Default impl 17 Thursday 21 October 2010
1 Mindset 2 Context 3 Behaviour 4 Relations 5 Implementation 6 Efficiency Implementation dynamic method pre-dispatch UILabel @property NSString *text @property UIFont *font ... Portrait impl - (void)Portrait_drawTextInRect:(CGRect)rect - (void)Landscape_drawTextInRect:(CGRect)rect Landscape impl - (void)Default_drawTextInRect:(CGRect)rect - (void)drawTextInRect:(CGRect)rect Default impl 17 Thursday 21 October 2010
1 Mindset 2 Context 3 Behaviour 4 Relations 5 Implementation 6 Efficiency Implementation dynamic method pre-dispatch UILabel @property NSString *text @property UIFont *font ... Portrait impl - (void)Portrait_drawTextInRect:(CGRect)rect - (void)Landscape_drawTextInRect:(CGRect)rect Landscape impl - (void)Default_drawTextInRect:(CGRect)rect - (void)drawTextInRect:(CGRect)rect Default impl 17 Thursday 21 October 2010
1 Mindset 2 Context 3 Behaviour 4 Relations 5 Implementation 6 Efficiency Implementation dynamic method pre-dispatch UILabel @property NSString *text @property UIFont *font ... Portrait impl - (void)Portrait_drawTextInRect:(CGRect)rect - (void)Landscape_drawTextInRect:(CGRect)rect Landscape impl - (void)Default_drawTextInRect:(CGRect)rect - (void)drawTextInRect:(CGRect)rect Default impl [CONTEXT activateContextWithName: @"Landscape"]; 17 Thursday 21 October 2010
1 Mindset 2 Context 3 Behaviour 4 Relations 5 Implementation 6 Efficiency Implementation dynamic method pre-dispatch UILabel @property NSString *text @property UIFont *font ... Portrait impl - (void)Portrait_drawTextInRect:(CGRect)rect - (void)Landscape_drawTextInRect:(CGRect)rect Landscape impl - (void)Default_drawTextInRect:(CGRect)rect - (void)drawTextInRect:(CGRect)rect Default impl [CONTEXT activateContextWithName: @"Landscape"]; 17 Thursday 21 October 2010
1 Mindset 2 Context 3 Behaviour 4 Relations 5 Implementation 6 Efficiency Implementation dynamic method pre-dispatch UILabel @property NSString *text @property UIFont *font ... Portrait impl - (void)Portrait_drawTextInRect:(CGRect)rect - (void)Landscape_drawTextInRect:(CGRect)rect Landscape impl - (void)Default_drawTextInRect:(CGRect)rect - (void)drawTextInRect:(CGRect)rect Default impl [CONTEXT activateContextWithName: @"Landscape"]; [CONTEXT deactivateContextWithName: @"Landscape"]; 17 Thursday 21 October 2010
1 Mindset 2 Context 3 Behaviour 4 Relations 5 Implementation 6 Efficiency Implementation dynamic method pre-dispatch UILabel @property NSString *text @property UIFont *font ... Portrait impl - (void)Portrait_drawTextInRect:(CGRect)rect - (void)Landscape_drawTextInRect:(CGRect)rect Landscape impl - (void)Default_drawTextInRect:(CGRect)rect - (void)drawTextInRect:(CGRect)rect Default impl [CONTEXT activateContextWithName: @"Landscape"]; [CONTEXT deactivateContextWithName: @"Landscape"]; 17 Thursday 21 October 2010
1 Mindset 2 Context 3 Behaviour 4 Relations 5 Implementation 6 Efficiency Implementation dynamic method pre-dispatch UILabel @property NSString *text @property UIFont *font ... Portrait impl - (void)Portrait_drawTextInRect:(CGRect)rect - (void)Landscape_drawTextInRect:(CGRect)rect Landscape impl - (void)Default_drawTextInRect:(CGRect)rect - (void)drawTextInRect:(CGRect)rect Default impl [CONTEXT activateContextWithName: @"Landscape"]; [CONTEXT deactivateContextWithName: @"Landscape"]; ‣ no additional cost for method invocations ‣ cost incurred at context switching time 17 Thursday 21 October 2010
1 Mindset 2 Context 3 Behaviour 4 Relations 5 Implementation 6 Efficiency What is more efficient? Subjective-C Objective-C context-specific methods conditional statements #context C1 -(void) test:(int) mode { -(void) test { result = 1; } if (mode == 1) result = 1; ... ... #context CN -(void) test else if (mode == N) { result = N; } result = N; -(void) test else { result = 0; } result = 0; } 18 Thursday 21 October 2010
1 Mindset 2 Context 3 Behaviour 4 Relations 5 Implementation 6 Efficiency Benchmark Setup Subjective-C #context C1 -(void) test for (int i = 0; i < 1000; i++) { { result = 1; } // switch context ... if (i % 2) [CONTEXT activateContextWithName:@"CK"]; #context CK else -(void) test [CONTEXT deactivateContextWithName:@"CK"]; { result = K; } // call test method repeatedly ... for (int j = 0; j < M; j++) [self test]; #context CN } -(void) test { result = N; } -(void) test { result = 0; } 19 Thursday 21 October 2010
1 Mindset 2 Context 3 Behaviour 4 Relations 5 Implementation 6 Efficiency Benchmark Setup Subjective-C #context C1 -(void) test for (int i = 0; i < 1000; i++) { { result = 1; } // switch context ... if (i % 2) [CONTEXT activateContextWithName:@"CK"]; #context CK else -(void) test [CONTEXT deactivateContextWithName:@"CK"]; { result = K; } // call test method repeatedly ... for (int j = 0; j < M; j++) [self test]; #context CN } -(void) test { result = N; } N: number of variations -(void) test K: selected branch { result = 0; } M: method calls per mode switch 19 Thursday 21 October 2010
1 Mindset 2 Context 3 Behaviour 4 Relations 5 Implementation 6 Efficiency Benchmark Setup Objective-C -(void) test:(int) mode { for (int i = 0; i < 1000; i++) { if (mode == 1) result = 1; // toggle operation mode if (i % 2) ... mode = K; else if (mode == K) mode = 0; result = K; // call test method repeatedly ... for (int j = 0; j < M; j++) [self test: mode]; else if (mode == N) } result = N; else N: number of variations result = 0; K: selected branch } M: method calls per mode switch 20 Thursday 21 October 2010
e case of 1 Mindset 2 Context 3 Behaviour 4 Relations 5 Implementation 6 Efficiency Fig. 6. N K M∗ N: number of variations 5 1 8230 10 1 4708 K: selected branch 50 5 1 5 3405 4521 M: method calls per context switch 10 10 2653 50 50 1148 105 ting point M ∗ between Subjective-C and Objective-C. Subjective-C 104 Objective-C parent in Fig. 6 because of the logarithmic scale. 103 milliseconds M∗ 102 101 100 10−1 100 101 102 103 104 105 method calls per context switch (M) Fig. 6. Performance comparison using logarithmic scale (N = 50, K = 50). iPhone 3GS, iOS 4.0 21 Thursday 21 October 2010
1 Mindset 2 Context 3 Behaviour 4 Relations 5 Implementation 6 Efficiency Subjective-C ✓ Context-oriented programming for a C-flavoured language ✓ Runs on mobile phones ✓ Run-time behaviour adaptation of any component (incl. 3rd party) ✓ Permits clean modularisation of adaptations ✓ Maximises adaptation points while avoiding architectural burden ✓ Context interdependency system ✓ Context declaration language ✓ Can be more efficient than dynamic dispatch ➡ Thread-local adaptations ➡ Improving efficiency ➡ Usability (IDE integration) ➡ Ensure behaviour consistency Thursday 21 October 2010
1 Mindset 2 Context 3 Behaviour 4 Relations 5 Implementation 6 Efficiency Subjective-C ✓ Context-oriented programming for a C-flavoured language ✓ Runs on mobile phones ✓ Run-time behaviour adaptation of any component (incl. 3rd party) ✓ Permits clean modularisation of adaptations ✓ Maximises adaptation points while avoiding architectural burden ✓ Context interdependency system ✓ Context declaration language ✓ Can be more efficient than dynamic dispatch ➡ Thread-local adaptations ➡ Improving efficiency ➡ Usability (IDE integration) Time for questions! ➡ Ensure behaviour consistency http://ambience.info.ucl.ac.be Thursday 21 October 2010

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Subjective-C: Bringing Context to Mobile Platform Programming

  • 1. 3rd International Conference on Software Language Engineering Subjective-C Bringing Context to Mobile Platform Programming ICTEAM / UCLouvain / Belgium Sebastián González Alfredo Cádiz Nicolás Cardozo Jean-Christophe Libbrecht Kim Mens Julien Goffaux 13 October 2010 Thursday 21 October 2010
  • 2. 3rd International Conference on Software Language Engineering Subjective-C Bringing Context to Mobile Platform Programming ICTEAM / UCLouvain / Belgium Sebastián González Sebastián González Alfredo Cádiz Nicolás Cardozo Jean-Christophe Libbrecht Kim Mens Kim Mens Julien Goffaux 13 October 2010 Thursday 21 October 2010
  • 3. 3rd International Conference on Software Language Engineering Subjective-C Bringing Context to Mobile Platform Programming ICTEAM / UCLouvain / Belgium Sebastián González Sebastián González Alfredo Cádiz Nicolás Cardozo Jean-Christophe Libbrecht Kim Mens Kim Mens Julien Goffaux 13 October 2010 Thursday 21 October 2010
  • 4. Research Context 2 Thursday 21 October 2010
  • 5. Research Goal Programming Mindset Towards a Mindset Shift programming in isolation programming in context ? ? ? ? ? ? 3 Thursday 21 October 2010
  • 6. Contemporary Solution conditional statements class phone { method receive ( call ) { if ( phone.isOffHook( ) ) play( phone.callWaitingSignal( ), 2 ); else if ( phone.environment( ).acoustics( ).isQuiet( ) ) phone.vibrate( 5 ); else if ( phone.user( ).isUnavailable( ) ) forwardCall( call, phone.forwardNumber( ) ); else play( phone.ringTone( ), 10 ); } 4 Thursday 21 October 2010
  • 7. Contemporary Solution conditional statements class phone { method receive ( call ) { if ( phone.isOffHook( ) ) play( phone.callWaitingSignal( ), 2 ); else if ( phone.environment( ).acoustics( ).isQuiet( ) ) phone.vibrate( 5 ); else if ( phone.user( ).isUnavailable( ) ) forwardCall( call, phone.forwardNumber( ) ); else play( phone.ringTone( ), 10 ); } 4 Thursday 21 October 2010
  • 8. Contemporary Solution conditional statements class phone { method receive ( call ) { if ( phone.isOffHook( ) ) play( phone.callWaitingSignal( ), 2 ); else if ( phone.environment( ).acoustics( ).isQuiet( ) ) phone.vibrate( 5 ); · else if ( phone.user( ).isUnavailable( ) ) forwardCall( call, phone.forwardNumber( ) ); else play( phone.ringTone( ), 10 ); } 4 Thursday 21 October 2010
  • 9. Contemporary Solution conditional statements class phone { method receive ( call ) { if ( phone.isOffHook( ) ) play( phone.callWaitingSignal( ), 2 ); else if ( phone.environment( ).acoustics( ).isQuiet( ) ) phone.vibrate( 5 ); · else if ( phone.user( ).isUnavailable( ) ) forwardCall( call, phone.forwardNumber( ) ); else play( phone.ringTone( ), 10 ); } 4 Thursday 21 October 2010
  • 10. Contemporary Solution conditional statements class phone { method receive ( call ) { if ( phone.isOffHook( ) ) play( phone.callWaitingSignal( ), 2 ); else if ( phone.environment( ).acoustics( ).isQuiet( ) ) phone.vibrate( 5 ); · else if ( phone.user( ).isUnavailable( ) ) forwardCall( call, phone.forwardNumber( ) ); else play( phone.ringTone( ), 10 ); ∅ } 4 Thursday 21 October 2010
  • 11. Contemporary Solution conditional statements class phone { method receive ( call ) { if ( phone.isOffHook( ) ) play( phone.callWaitingSignal( ), 2 ); else if ( phone.environment( ).acoustics( ).isQuiet( ) ) phone.vibrate( 5 ); · else if ( phone.user( ).isUnavailable( ) ) forwardCall( call, phone.forwardNumber( ) ); else play( phone.ringTone( ), 10 ); ∅ } Tangled Scattered Fixed 4 Thursday 21 October 2010
  • 12. Contemporary Solution special software architectures class Phone { attribute strategy; method receive ( call ) { strategy.receive ( call ); } } 5 Thursday 21 October 2010
  • 13. Contemporary Solution special software architectures class DefaultStrategy { method receive ( call ) { ... } } class QuietStrategy class Phone { method receive ( call ) { ... } } · { attribute strategy; method receive ( call ) class OffHookStrategy { strategy.receive ( call ); } } { method receive ( call ) { ... } } class UnavailableStrategy { method receive ( call ) { ... } } 5 Thursday 21 October 2010
  • 14. Contemporary Solution special software architectures class DefaultStrategy { method receive ( call ) { ... } } class QuietStrategy class Phone { method receive ( call ) { ... } } · { attribute strategy; method receive ( call ) class OffHookStrategy { strategy.receive ( call ); } } { method receive ( call ) { ... } } class UnavailableStrategy { method receive ( call ) { ... } } 5 Thursday 21 October 2010
  • 15. Contemporary Solution special software architectures class DefaultStrategy { method receive ( call ) { ... } } class QuietStrategy class Phone { method receive ( call ) { ... } } { attribute strategy; method receive ( call ) class OffHookStrategy { strategy.receive ( call ); } } { method receive ( call ) { ... } } class UnavailableStrategy { method receive ( call ) { ... } } Infrastructural burden Fixed adaptation points 5 Thursday 21 October 2010
  • 16. Solution Language engineering approach 6 Thursday 21 October 2010
  • 17. Solution Language engineering approach Multiple dispatch Prototypes PMD CLOS Self Smalltalk 6 Thursday 21 October 2010
  • 18. Solution Language engineering approach Subjective Programming Multiple dispatch Prototypes PMD CLOS Self Smalltalk 6 Thursday 21 October 2010
  • 19. Solution Language engineering approach Context Management Subjective Programming Multiple dispatch Prototypes PMD CLOS Self Smalltalk 6 Thursday 21 October 2010
  • 20. Solution Language engineering approach Context-Oriented Programming Context Management Subjective Programming Multiple dispatch Prototypes PMD CLOS Self Smalltalk 6 Thursday 21 October 2010
  • 21. Solution Language engineering approach Ambience [DLS’07] Context-Oriented Programming Context Management Subjective Programming Multiple dispatch Prototypes PMD CLOS Self Smalltalk 6 Thursday 21 October 2010
  • 22. Solution Language engineering approach Ambience [DLS’07] Context-Oriented Programming Context Management Subjective Programming Multiple dispatch Prototypes PMD CLOS Self Smalltalk 6 Thursday 21 October 2010
  • 23. Solution Language engineering approach Ambience [DLS’07] Context-Oriented Programming Context Management Subjective Programming Multiple dispatch Single dispatch Prototypes Open Classes PMD Objective-C CLOS C Self Smalltalk 6 Thursday 21 October 2010
  • 24. Solution Language engineering approach Ambience [DLS’07] Context-Oriented Programming Context Management Subjective Programming Subjective Programming Multiple dispatch Single dispatch Prototypes Open Classes PMD Objective-C CLOS C Self Smalltalk 6 Thursday 21 October 2010
  • 25. Solution Language engineering approach Ambience [DLS’07] Context-Oriented Programming Context Management Context Management Subjective Programming Subjective Programming Multiple dispatch Single dispatch Prototypes Open Classes PMD Objective-C CLOS C Self Smalltalk 6 Thursday 21 October 2010
  • 26. Solution Language engineering approach Ambience [DLS’07] Context-Oriented Programming Context-Oriented Programming Context Management Context Management Subjective Programming Subjective Programming Multiple dispatch Single dispatch Prototypes Open Classes PMD Objective-C CLOS C Self Smalltalk 6 Thursday 21 October 2010
  • 27. Solution Language engineering approach Ambience [DLS’07] Subjective-C Context-Oriented Programming Context-Oriented Programming Context Management Context Management Subjective Programming Subjective Programming Multiple dispatch Single dispatch Prototypes Open Classes PMD Objective-C CLOS C Self Smalltalk 6 Thursday 21 October 2010
  • 28. Solution Language engineering approach Ambience [DLS’07] Subjective-C Context-Oriented Programming Context-Oriented Programming Context Management Context Management Subjective Programming Subjective Programming Multiple dispatch Single dispatch Prototypes Open Classes PMD Objective-C CLOS C Self Smalltalk 6 Thursday 21 October 2010
  • 29. Subjective-C 1 General mindset 2 Context definition 3 Context-specific behaviour 4 Context relations 5 Implementation 6 Efficiency 7 Thursday 21 October 2010
  • 30. 1 Mindset 2 Context 3 Behaviour 4 Relations 5 Implementation 6 Efficiency Context-Aware System Architecture World Sensors Actuators Subjective-C Context Application Discovery Behaviour external internal context effect context information arbitrated context Context changes Active Management Context 8 Thursday 21 October 2010
  • 31. 1 Mindset 2 Context 3 Behaviour 4 Relations 5 Implementation 6 Efficiency What is context? Computationally Well-defined situation accessible information (Contexts) Z axis = 0.03 Landscape orientation Battery charge = 220 mAh Low battery charge Idle cycles = 11 MHz High CPU load Location = 51°26′N 5°29′E Eindhoven no semantics action can be taken situations can be reified 9 Thursday 21 October 2010
  • 32. 1 Mindset 2 Context 3 Behaviour 4 Relations 5 Implementation 6 Efficiency Case Study 10 Thursday 21 October 2010
  • 33. 1 Mindset 2 Context 3 Behaviour 4 Relations 5 Implementation 6 Efficiency Case Study UILabel class drawTextInRect: Draws the receiver’s text in the specified rectangle. - (void)drawTextInRect:(CGRect)rect Parameters rect The rectangle in which to draw the text. Discussion You should not call this method directly. This method should only be overridden by subclasses that want to modify the default drawing behavior for the label’s text. Availability Available in iOS 2.0 and later. Declared In UILabel.h 11 Thursday 21 October 2010
  • 34. 1 Mindset 2 Context 3 Behaviour 4 Relations 5 Implementation 6 Efficiency Case Study UILabel class drawTextInRect: Draws the receiver’s text in the specified rectangle. - (void)drawTextInRect:(CGRect)rect Parameters rect The rectangle in which to draw the text. Discussion You should not call this method directly. This method should only be overridden by subclasses that want to modify the default drawing behavior for the label’s text. Availability Available in iOS 2.0 and later. Declared In UILabel.h 11 Thursday 21 October 2010
  • 35. 1 Mindset 2 Context 3 Behaviour 4 Relations 5 Implementation 6 Efficiency Subjective-C: Look & Feel @implementation UILabel (color) #context Landscape - (void)drawTextInRect:(CGRect)rect { self.textColor = [UIColor greenColor]; [superContext drawTextInRect:rect]; } @end 12 Thursday 21 October 2010
  • 36. 1 Mindset 2 Context 3 Behaviour 4 Relations 5 Implementation 6 Efficiency Subjective-C: Look & Feel Open classes @implementation UILabel (color) Objective-C #context Landscape - (void)drawTextInRect:(CGRect)rect { self.textColor = [UIColor greenColor]; [superContext drawTextInRect:rect]; } @end 12 Thursday 21 October 2010
  • 37. 1 Mindset 2 Context 3 Behaviour 4 Relations 5 Implementation 6 Efficiency Subjective-C: Look & Feel Open classes @implementation UILabel (color) Objective-C COP #context Landscape Subjective-C - (void)drawTextInRect:(CGRect)rect { self.textColor = [UIColor greenColor]; [superContext drawTextInRect:rect]; } @end 12 Thursday 21 October 2010
  • 38. 1 Mindset 2 Context 3 Behaviour 4 Relations 5 Implementation 6 Efficiency Subjective-C: Look & Feel Open classes @implementation UILabel (color) Objective-C COP #context Landscape Subjective-C - (void)drawTextInRect:(CGRect)rect { self.textColor = [UIColor greenColor]; [superContext drawTextInRect:rect]; } @end ✓ Adaptation of any existing component ✓ No access to original source code needed ✓ Adaptations can be cleanly modularised 12 Thursday 21 October 2010
  • 39. 1 Mindset 2 Context 3 Behaviour 4 Relations 5 Implementation 6 Efficiency Context Relations Strong Inclusion Eindhoven Netherlands Weak Inclusion Museum Quiet Requirement HDVideo BatteryHigh Exclusion Landscape Portrait 13 Thursday 21 October 2010
  • 40. 1 Mindset 2 Context 3 Behaviour 4 Relations 5 Implementation 6 Efficiency Programmatic Context Definition // Create contexts Context* Room = [[Context alloc] initWithName:@"Room"]; Context* Bedroom = [[Context alloc] initWithName:@"Bedroom"]; Context* Day = [[Context alloc] initWithName:@"Day"]; Context* Night = [[Context alloc] initWithName:@"Night"]; ... // Register contexts [CONTEXT addContext:Room]; [CONTEXT addContext:Bedroom]; [CONTEXT addContext:Day]; [CONTEXT addContext:Night]; ... // Establish context relations [Day addExclusionRelationWith:Night]; [Bedroom addHardInclusionRelationWith:Room]; ... 14 Thursday 21 October 2010
  • 41. 1 Mindset 2 Context 3 Behaviour 4 Relations 5 Implementation 6 Efficiency Context Declaration Language Contexts: Relations: // Create contexts Context* Room = [[Context alloc] initWithName:@"Room"]; Context* Bedroom = [[Context alloc] initWithName:@"Bedroom"]; >< Night Room Day Context* Livingroom Day = [[Context alloc] initWithName:@"Day"]; Sun >< Rain Context* Kitchen Night = [[Context alloc] initWithName:@"Night"]; ... Bedroom Livingroom -> TV Bathroom Livingroom -> Window // Register contexts Day Livingroom -> Luminosity [CONTEXT addContext:Room]; [CONTEXT addContext:Bedroom]; Night Livingroom -> Temperature [CONTEXT addContext:Day]; Kitchen -> Luminosity [CONTEXT addContext:Night]; TV Bedroom -> Temperature ... Window Bedroom -> Luminosity Temperature Bedroom -> Window // Establish context relations Luminosity Bathroom -> Temperature [Day addExclusionRelationWith:Night]; [Bedroom addHardInclusionRelationWith:Room]; Bathroom -> Luminosity ... Sun Rain Bathroom => Room Electricity Kitchen => Room Livingroom => Room Bedroom => Room TV =< Electricity Luminosity =< Electricity Window =< Sun 14 Thursday 21 October 2010
  • 42. 1 Mindset 2 Context 3 Behaviour 4 Relations 5 Implementation 6 Efficiency Context Declaration Language // Create contexts Context* Room = [[Context alloc] initWithName:@"Room"]; Context* Bedroom = [[Context alloc] initWithName:@"Bedroom"]; Context* Day = [[Context alloc] initWithName:@"Day"]; Context* Night = [[Context alloc] initWithName:@"Night"]; ... // Register contexts [CONTEXT addContext:Room]; [CONTEXT addContext:Bedroom]; [CONTEXT addContext:Day]; [CONTEXT addContext:Night]; ... // Establish context relations [Day addExclusionRelationWith:Night]; [Bedroom addHardInclusionRelationWith:Room]; ... 14 Thursday 21 October 2010
  • 43. 1 Mindset 2 Context 3 Behaviour 4 Relations 5 Implementation 6 Efficiency Other Generated Code // Create contexts Context* Room = [[Context alloc] initWithName:@"Room"]; Context* Bedroom = [[Context alloc] initWithName:@"Bedroom"]; Context* Day = [[Context alloc] initWithName:@"Day"]; Context* Night = [[Context alloc] initWithName:@"Night"]; ... // Register contexts [CONTEXT addContext:Room]; [CONTEXT addContext:Bedroom]; [CONTEXT addContext:Day]; [CONTEXT addContext:Night]; ... // Establish context relations #context Bedroom [Day addExclusionRelationWith:Night]; -(Context*) getActiveRoom{ [Bedroom addHardInclusionRelationWith:Room]; ! return [CONTEXT getContext:@"Bedroom"]; ... } // Register context-specific methods [MANAGER addMethod:@selector(Context_Bedroom_getActiveRoom) forClass:[DomoticsServerViewController class] forContextNames:[[NSSet alloc] initWithObjects:@"Bedroom" ,nil] withDefautSel:@selector(getActiveRoom) withPriority:0]; ... 14 Thursday 21 October 2010
  • 44. 1 Mindset 2 Context 3 Behaviour 4 Relations 5 Implementation 6 Efficiency Other Generated Code // Create contexts Context* Room = [[Context alloc] initWithName:@"Room"]; Context* Bedroom = [[Context alloc] initWithName:@"Bedroom"]; Context* Day = [[Context alloc] initWithName:@"Day"]; Context* Night = [[Context alloc] initWithName:@"Night"]; ... // Register contexts [CONTEXT addContext:Room]; [CONTEXT addContext:Bedroom]; [CONTEXT addContext:Day]; [CONTEXT addContext:Night]; ... // Establish context relations [Day addExclusionRelationWith:Night]; [Bedroom addHardInclusionRelationWith:Room]; ... // Register context-specific methods [MANAGER addMethod:@selector(Context_Bedroom_getActiveRoom) forClass:[DomoticsServerViewController class] forContextNames:[[NSSet alloc] initWithObjects:@"Bedroom" ,nil] withDefautSel:@selector(getActiveRoom) withPriority:0]; ... 14 Thursday 21 October 2010
  • 45. 1 Mindset 2 Context 3 Behaviour 4 Relations 5 Implementation 6 Efficiency Application Contexts @implementation LowpassFilter -(void)addAcceleration:(UIAcceleration*)accel { ! double alpha = filterConstant; ! ! if(adaptive) ! ! alpha = ... // big formula to calculate the alpha level ! ! x = accel.x * alpha + x * (1.0 - alpha); ! y = accel.y * alpha + y * (1.0 - alpha); ! z = accel.z * alpha + z * (1.0 - alpha); } -(NSString*)name { ! return adaptive ? @"Adaptive Lowpass Filter" : @"Lowpass Filter"; } ... 15 Thursday 21 October 2010
  • 46. 1 Mindset 2 Context 3 Behaviour 4 Relations 5 Implementation 6 Efficiency Application Contexts @implementation LowpassFilter #context LowPassFilter -(void)addAcceleration:(UIAcceleration*)accel { ! double alpha = [self getAlpha:accel]; ! ! x = accel.x * alpha + x * (1.0 - alpha); ! y = accel.y * alpha + y * (1.0 - alpha); ! z = accel.z * alpha + z * (1.0 - alpha); } #context !Adaptive -(double) getAlpha:(UIAcceleration*)accel{ ! return filterConstant; } #context LowPassFilter Adaptive -(double) getAlpha:(UIAcceleration*)accel { ! return // big formula to calculate the alpha level; } 16 Thursday 21 October 2010
  • 47. 1 Mindset 2 Context 3 Behaviour 4 Relations 5 Implementation 6 Efficiency Application Contexts @implementation LowpassFilter Contexts: #context LowPassFilter Adaptive -(void)addAcceleration:(UIAcceleration*)accel Paused { LowPassFilter ! double alpha = [self getAlpha:accel]; HighPassFilter ! ! x = accel.x * alpha + x * (1.0 - alpha); Filter ! y = accel.y * alpha + y * (1.0 - alpha); Relations: ! z = accel.z * alpha + z * (1.0 - alpha); } LowPassFilter >< HighPassFilter LowPassFilter => Filter #context !Adaptive HighPassFilter => Filter -(double) getAlpha:(UIAcceleration*)accel{ ! return filterConstant; } #context LowPassFilter Adaptive -(double) getAlpha:(UIAcceleration*)accel { ! return // big formula to calculate the alpha level; } 16 Thursday 21 October 2010
  • 48. 1 Mindset 2 Context 3 Behaviour 4 Relations 5 Implementation 6 Efficiency Implementation dynamic method pre-dispatch UILabel @property NSString *text @property UIFont *font ... Portrait impl - (void)Portrait_drawTextInRect:(CGRect)rect - (void)Landscape_drawTextInRect:(CGRect)rect Landscape impl - (void)Default_drawTextInRect:(CGRect)rect - (void)drawTextInRect:(CGRect)rect Default impl 17 Thursday 21 October 2010
  • 49. 1 Mindset 2 Context 3 Behaviour 4 Relations 5 Implementation 6 Efficiency Implementation dynamic method pre-dispatch UILabel @property NSString *text @property UIFont *font ... vtable Portrait impl - (void)Portrait_drawTextInRect:(CGRect)rect - (void)Landscape_drawTextInRect:(CGRect)rect Landscape impl - (void)Default_drawTextInRect:(CGRect)rect - (void)drawTextInRect:(CGRect)rect Default impl 17 Thursday 21 October 2010
  • 50. 1 Mindset 2 Context 3 Behaviour 4 Relations 5 Implementation 6 Efficiency Implementation dynamic method pre-dispatch UILabel @property NSString *text @property UIFont *font ... Portrait impl - (void)Portrait_drawTextInRect:(CGRect)rect - (void)Landscape_drawTextInRect:(CGRect)rect Landscape impl - (void)Default_drawTextInRect:(CGRect)rect - (void)drawTextInRect:(CGRect)rect Default impl 17 Thursday 21 October 2010
  • 51. 1 Mindset 2 Context 3 Behaviour 4 Relations 5 Implementation 6 Efficiency Implementation dynamic method pre-dispatch UILabel @property NSString *text @property UIFont *font ... Portrait impl - (void)Portrait_drawTextInRect:(CGRect)rect - (void)Landscape_drawTextInRect:(CGRect)rect Landscape impl - (void)Default_drawTextInRect:(CGRect)rect - (void)drawTextInRect:(CGRect)rect Default impl 17 Thursday 21 October 2010
  • 52. 1 Mindset 2 Context 3 Behaviour 4 Relations 5 Implementation 6 Efficiency Implementation dynamic method pre-dispatch UILabel @property NSString *text @property UIFont *font ... Portrait impl - (void)Portrait_drawTextInRect:(CGRect)rect - (void)Landscape_drawTextInRect:(CGRect)rect Landscape impl - (void)Default_drawTextInRect:(CGRect)rect - (void)drawTextInRect:(CGRect)rect Default impl [CONTEXT activateContextWithName: @"Landscape"]; 17 Thursday 21 October 2010
  • 53. 1 Mindset 2 Context 3 Behaviour 4 Relations 5 Implementation 6 Efficiency Implementation dynamic method pre-dispatch UILabel @property NSString *text @property UIFont *font ... Portrait impl - (void)Portrait_drawTextInRect:(CGRect)rect - (void)Landscape_drawTextInRect:(CGRect)rect Landscape impl - (void)Default_drawTextInRect:(CGRect)rect - (void)drawTextInRect:(CGRect)rect Default impl [CONTEXT activateContextWithName: @"Landscape"]; 17 Thursday 21 October 2010
  • 54. 1 Mindset 2 Context 3 Behaviour 4 Relations 5 Implementation 6 Efficiency Implementation dynamic method pre-dispatch UILabel @property NSString *text @property UIFont *font ... Portrait impl - (void)Portrait_drawTextInRect:(CGRect)rect - (void)Landscape_drawTextInRect:(CGRect)rect Landscape impl - (void)Default_drawTextInRect:(CGRect)rect - (void)drawTextInRect:(CGRect)rect Default impl [CONTEXT activateContextWithName: @"Landscape"]; [CONTEXT deactivateContextWithName: @"Landscape"]; 17 Thursday 21 October 2010
  • 55. 1 Mindset 2 Context 3 Behaviour 4 Relations 5 Implementation 6 Efficiency Implementation dynamic method pre-dispatch UILabel @property NSString *text @property UIFont *font ... Portrait impl - (void)Portrait_drawTextInRect:(CGRect)rect - (void)Landscape_drawTextInRect:(CGRect)rect Landscape impl - (void)Default_drawTextInRect:(CGRect)rect - (void)drawTextInRect:(CGRect)rect Default impl [CONTEXT activateContextWithName: @"Landscape"]; [CONTEXT deactivateContextWithName: @"Landscape"]; 17 Thursday 21 October 2010
  • 56. 1 Mindset 2 Context 3 Behaviour 4 Relations 5 Implementation 6 Efficiency Implementation dynamic method pre-dispatch UILabel @property NSString *text @property UIFont *font ... Portrait impl - (void)Portrait_drawTextInRect:(CGRect)rect - (void)Landscape_drawTextInRect:(CGRect)rect Landscape impl - (void)Default_drawTextInRect:(CGRect)rect - (void)drawTextInRect:(CGRect)rect Default impl [CONTEXT activateContextWithName: @"Landscape"]; [CONTEXT deactivateContextWithName: @"Landscape"]; ‣ no additional cost for method invocations ‣ cost incurred at context switching time 17 Thursday 21 October 2010
  • 57. 1 Mindset 2 Context 3 Behaviour 4 Relations 5 Implementation 6 Efficiency What is more efficient? Subjective-C Objective-C context-specific methods conditional statements #context C1 -(void) test:(int) mode { -(void) test { result = 1; } if (mode == 1) result = 1; ... ... #context CN -(void) test else if (mode == N) { result = N; } result = N; -(void) test else { result = 0; } result = 0; } 18 Thursday 21 October 2010
  • 58. 1 Mindset 2 Context 3 Behaviour 4 Relations 5 Implementation 6 Efficiency Benchmark Setup Subjective-C #context C1 -(void) test for (int i = 0; i < 1000; i++) { { result = 1; } // switch context ... if (i % 2) [CONTEXT activateContextWithName:@"CK"]; #context CK else -(void) test [CONTEXT deactivateContextWithName:@"CK"]; { result = K; } // call test method repeatedly ... for (int j = 0; j < M; j++) [self test]; #context CN } -(void) test { result = N; } -(void) test { result = 0; } 19 Thursday 21 October 2010
  • 59. 1 Mindset 2 Context 3 Behaviour 4 Relations 5 Implementation 6 Efficiency Benchmark Setup Subjective-C #context C1 -(void) test for (int i = 0; i < 1000; i++) { { result = 1; } // switch context ... if (i % 2) [CONTEXT activateContextWithName:@"CK"]; #context CK else -(void) test [CONTEXT deactivateContextWithName:@"CK"]; { result = K; } // call test method repeatedly ... for (int j = 0; j < M; j++) [self test]; #context CN } -(void) test { result = N; } N: number of variations -(void) test K: selected branch { result = 0; } M: method calls per mode switch 19 Thursday 21 October 2010
  • 60. 1 Mindset 2 Context 3 Behaviour 4 Relations 5 Implementation 6 Efficiency Benchmark Setup Objective-C -(void) test:(int) mode { for (int i = 0; i < 1000; i++) { if (mode == 1) result = 1; // toggle operation mode if (i % 2) ... mode = K; else if (mode == K) mode = 0; result = K; // call test method repeatedly ... for (int j = 0; j < M; j++) [self test: mode]; else if (mode == N) } result = N; else N: number of variations result = 0; K: selected branch } M: method calls per mode switch 20 Thursday 21 October 2010
  • 61. e case of 1 Mindset 2 Context 3 Behaviour 4 Relations 5 Implementation 6 Efficiency Fig. 6. N K M∗ N: number of variations 5 1 8230 10 1 4708 K: selected branch 50 5 1 5 3405 4521 M: method calls per context switch 10 10 2653 50 50 1148 105 ting point M ∗ between Subjective-C and Objective-C. Subjective-C 104 Objective-C parent in Fig. 6 because of the logarithmic scale. 103 milliseconds M∗ 102 101 100 10−1 100 101 102 103 104 105 method calls per context switch (M) Fig. 6. Performance comparison using logarithmic scale (N = 50, K = 50). iPhone 3GS, iOS 4.0 21 Thursday 21 October 2010
  • 62. 1 Mindset 2 Context 3 Behaviour 4 Relations 5 Implementation 6 Efficiency Subjective-C ✓ Context-oriented programming for a C-flavoured language ✓ Runs on mobile phones ✓ Run-time behaviour adaptation of any component (incl. 3rd party) ✓ Permits clean modularisation of adaptations ✓ Maximises adaptation points while avoiding architectural burden ✓ Context interdependency system ✓ Context declaration language ✓ Can be more efficient than dynamic dispatch ➡ Thread-local adaptations ➡ Improving efficiency ➡ Usability (IDE integration) ➡ Ensure behaviour consistency Thursday 21 October 2010
  • 63. 1 Mindset 2 Context 3 Behaviour 4 Relations 5 Implementation 6 Efficiency Subjective-C ✓ Context-oriented programming for a C-flavoured language ✓ Runs on mobile phones ✓ Run-time behaviour adaptation of any component (incl. 3rd party) ✓ Permits clean modularisation of adaptations ✓ Maximises adaptation points while avoiding architectural burden ✓ Context interdependency system ✓ Context declaration language ✓ Can be more efficient than dynamic dispatch ➡ Thread-local adaptations ➡ Improving efficiency ➡ Usability (IDE integration) Time for questions! ➡ Ensure behaviour consistency http://ambience.info.ucl.ac.be Thursday 21 October 2010