Masters Thesis Defense:Aspectual ConceptsJohn J. Sung

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OutlineMotivationJPM and Demeter ConceptsDemeter integrated with AspectJ ( AJ) AJ Semantics/Syntax AJ System ArchitectureConclusion

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MotivationAspect Oriented Software Development Gaining Momentum1st International Conference on AOSDAspectJ, DemeterJ, ConcernJ, HyperJ, etc.AOSD is Relatively YoungDemeter C++ ~1989DemeterJ ~ 1996AspectJ ~1997

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QuestionsWhat are the fundamental concepts behind AOSD?How are these concepts related?How can these concepts be combined?What are the fundamental problems that software language features attempt to solve?

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Join Point Model (JPM)Fundamental ConceptsJoin Point, Pointcut, Advice, Aspect, IntroductionConcepts applied to call graph in AspectJIntroduction also applied to class graph

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AspectJ Abstraction of ProgramsCall GraphPointcuts++Advice=>Program

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AspectJ Abstraction of Programsfoo(){x = 0;if (x < 0) throw KException;}Class Barint x;b1.foo();Class C1within(Bar)Aspect Abefore() : within(Bar) {}

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Another ViewJava ProgramAspectJAdvicepointcutadvice bodyjoin point

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DemeterFundamental ConceptsClass Graph, Strategy, Visitor, AdviceConcepts applied to data structures, i.e. class graphJourney Metaphor

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Journey MetaphorConcepts in Demeter create an image of a person on a journey

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Demeter Abstraction of ProgramsClass GraphStrategyGraph++VisitorAdvices=>Program

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Demeter Abstraction of Programs=>before(..)after(..)before(..)ClassGraphStrategyGraphTraversalGraphVisitorAdvices

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Combining ConceptsApplication of JPM to DemeterClass graph is built of classes and edgesJoin points become the points along traversalsAdvices are executed at these join points

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Combining ConceptsApplication of Demeter to JPMCPU executes the traversal through the dynamic call graphCPU manages the dynamic call graphAdvices are for the one visitor: CPU

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Demeter AspectJ: AJ Extends AspectJ with traversal capabilityDefines a traversal specification languageUses DJ to generate Class Graph, Traversal GraphGenerates the AspectJ implementation of the traversal using AspectJ introductionsImplemented using DemeterJ, DJ, AspectJBlending of JPM and Demeter Concepts

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Design of AJFirst DesignAdd syntax to AspectJ languageModify the open source ajcUse DJ and AspectJ to modify the behaviorSecond DesignUse ajc as the back endCreate a small language to describe traversalsUse DJ, AspectJ, DemeterJLess coupling with the AspectJ compiler

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Traversal Specification LanguageDesigned to have similar syntax to DJ and AspectJAllows users to specify Class Graph, Traversal, and VisitorGenerates AspectJ implementation of traversals using introductionsVisitor advices are called by using AspectJ advices

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Class Graph SpecificationDefault Class Graph

ClassGraph cgvar;

Class Graph Slice

ClassGraph cgvar = new ClassGraph(cg, strategy);

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Visitor SpecificationUses Java Reflection to obtain method signaturesRecognized Methodsaround, before, after, start, finish, returnValueVisitor DeclarationVisitor visitorClass;

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Traversal SpecificationDefault Traversal Specification

declare traversal tvar : strategy;

Traversal with Class Graph

declare traversal tvar(cgvar) : strategy;

Traversal with Visitor

declare traversal tvar(cgvar, visitorvar) : strategy;

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Aspect Specificationaspect aspectName { class graph declarations; traversal declarations; visitor declarations;}

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What AJ GeneratesFor each default and class graph slice traversalmethod void tvar() for the source node of the traversal strategyFor each traversal with visitormethod void tvar() for the source node of the traversal strategymethod void tvar(visitorClass) for the source node of the traversal strategyAppropriate AspectJ advices for each advice method in visitorClass

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A Simple Basket Exampleclass Basket { Basket(Fruit _f, Pencil _p) { f = _f; p = _p; } Basket(Fruit _f, Fruit _f2, Pencil _p) { f = _f; f2 = _f2; p = _p; } Fruit f, f2; Pencil p;}class Fruit { Fruit(Weight _w) { w = _w; } Weight w;}class Orange extends Fruit { Orange(Color _c) { super(null); c=_c;} Orange(Color _c, Weight _w) { super(_w); c = _c;} Color c;}class Pencil {}class Color { Color(String _s) { s = _s;} String s;}class Weight{ Weight(int _i) { i = _i;} int i; int get_i() { return i; }}

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A Simple Basket ExampleBasketFruitPencilpf, f2OrangeWeightColorwcStringsint i

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BasketVisitorclass BasketVisitor { int total;

public void start() {total = 0; }

public int returnValue() {return total; } void before(Weight w) {total += w.get_i(); }}

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Basket Traversalaspect BasketTraversal { ClassGraph default; ClassGraph myClassGraph = new ClassGraph(default, "from Basket to *"); Visitor BasketVisitor; declare traversal t1(myClassGraph,BasketVisitor) : "from Basket to Weight"; declare traversal t2(myClassGraph,BasketVisitor) : "from Basket via Orange to Weight";}

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Basket Main

class BasketMain { static public void main(String args[]) throws Exception {Basket b = new Basket(new Orange(new Color("orange"), new Weight(5)), new Fruit( new Weight(10)), new Pencil() );

BasketVisitor bv = new BasketVisitor();b.t1(bv);int totalWeight = bv.returnValue();System.out.println("Total weight of basket = " + totalWeight);b.t2(bv);

totalWeight = bv.returnValue();System.out.println("Total weight2 of basket = " + totalWeight); }}

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Generated Code for Visitor static BasketVisitor t1_visitor; public void Basket.t1(BasketVisitor v) { t1_visitor=v; t1_visitor.start(); t1(); } before(Weight host) : call(public void t1*()) && target(host) { t1_visitor.before(host); } void Basket.t1() { t1_copy0(); }

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Basket Class GraphBasketFruitPencilpf, f2OrangeWeightColorwcStringsint i

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Generated Code for Traversal // traversal t1 : {source: Basket -> target: Weight} with { } public void Basket.t1_copy0(){ if (f != null) t1_copy0_crossing_f(); if (f2 != null) t1_copy0_crossing_f2(); } public void Basket.t1_copy0_crossing_f() { f.t1_copy0();} public void Basket.t1_copy0_crossing_f2() { f2.t1_copy0();} public void Fruit.t1_copy0(){ if (w != null) t1_copy0_crossing_w(); } public void Fruit.t1_copy0_crossing_w() { w.t1_copy0();} public void Weight.t1_copy0(){ } public void Orange.t1_copy0(){ super.t1_copy0(); } pointcut pointcut_t1() : call(public void t1*()); before () : pointcut_t1 () { System.out.println(thisJoinPoint); }

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System ArchitectureDAJ MainParses command line argumentsManages the DAJ code generation phasesStub GenerationGenerates stubs for traversal methodsTraversal Generation CompilationCompiles using ajc the stubs, user code, and CreateClassGraph.java

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System ArchitectureTraversal GenerationUses DJ, Java Reflection, and DemeterJ to generate AspectJ traversal codeTraversal CompilationCompiles the generated traversal code with user code

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System ArchitectureStub GenerationTraversal Generation CompilationTraversal Generation Traversal Compilation DAJMainmethodcallshellshellshell

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AJ ProcessStub GenerationTraversal FilesGenerated StubsTraversal Generation CompilationClass FilesClass FilesTraversal Generation Traversal Compilation UserCodeCreateClassGraph.javaTraversalImplementationUser Code to DAJCode Provided by DAJIntermediate FilesFinal Application

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Traversal GenerationCreateClassGraph.javaintercepts the call to maininstantiates a ClassGraph using DJArguments and ClassGraphUses DJ to generate Traversal GraphTranslates the Traversal Graph to AspectJ introductionsVisitor code generationuses Java Reflection to obtain method signituresgenerates AspectJ advices for each visitor advice

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Example Run of AJ[denali: ~/demeter/daj/dev/basket2] > java edu.neu.ccs.demeter.daj.DAJ -main BasketMain -dtrv trav -ccg ../ccg/CreateClassGraph.java BasketMain.java BasketTraversal.trv BasketVisitor.java

%I - Generating Stubsprefix for stub: travGenerating Stub file: trav/BasketTraversal.java

%I - traversal generation compilationajc ../ccg/CreateClassGraph.java BasketMain.java BasketVisitor.java trav/BasketTraversal.java

%I - traversal generationjava BasketMain -d trav BasketTraversal.trv

%I - traversal compilationajc BasketMain.java BasketVisitor.java trav/BasketTraversal.java

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Measuring PerformanceTraversals implemented in DemeterJ, DJ, DAJVary the size of the Object GraphMeasure the elapsed time between start and finishSunBlade 100 running SunOS 5.8

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Performance Comparison

Chart1

23357732

40790848

551186362

601490570

DemeterJ

DJ

DAJ

Object Graph Size

Elapse Time (ms)

Sheet1

OG SizeDemeterJDJDAJ

500023357732

1000040790848

15000551186362

20000601490570

Sheet1

DemeterJ

DJ

DAJ

Object Graph Size

Elapse Time (ms)

Sheet2

Sheet3

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DemeterJ and AJ Performance

Chart2

2332

4048

5562

6070

DemeterJ

DAJ

Object Graph Size

Elapsed Time (ms)

Sheet1

OG SizeDemeterJDJDAJ

500023357732

1000040790848

15000551186362

20000601490570

Sheet1

DemeterJ

DJ

DAJ

Object Graph Size

Elapse Time (ms)

Sheet2

DemeterJ

DAJ

Object Graph Size

Elapsed Time (ms)

Sheet3

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Performance Comparison

Sheet1

OG SizeDemeterJDJDAJ

500023357732

1000040790848

15000551186362

20000601490570

Sheet1

DemeterJ

DJ

DAJ

Object Graph Size

Elapse Time (ms)

Sheet2

Sheet3

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Future AJ Improvementshttp://www.ccs.neu.edu/research/demeter/DAJTwo syntax supportedDJ/Java like styleAspectJs declare syntaxHandle CollectionsTraversal through Java CollectionsHandle interfacesGenerates Traversals correctly for interfaces

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QuestionsWhat are the fundamental concepts behind AOSD in Demeter and AspectJ?How are these concepts related?How can these concepts be combined?What are the fundamental problems that software language features attempt to solve?

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Software Design Concerns Organizational ConcernHow do I organize my code?Factorizational ConcernHow can I factor similar code?Specification ConcernWhat can I specify within the program?Interface ConcernHow can I interface with someone elses code?

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ConclusionsMetaphors used in Demeter and JPMConstruction and Journey MetaphorsUsage of one or the other depends on the users and applicationCan describe each otherCombinable

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ConclusionsDAJMixing Demeter with AspectJ conceptsUses DJ, DemeterJ and AspectJExtends AspectJ incrementallyFaster traversals than DJwww.ccs.neu.edu/research/demeter/DAJ

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ConclusionsSoftware Design ConcernsOrganizational, Factorizational, Specification, and InterfaceHow do programming features address SDC?How do SDCs related to AOP?Further research needed

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Future DirectionAnalyze the metaphors used in other toolsComposeJ, HyperJ, etc.Try combining these conceptsUse the Software Design Concerns to analyze AOP tools

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AspectJ from PARCAJEMETERJ(Demeter AspectJ)

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Referenceswww.ccs.neu.edu/research/demeter/DAJwww.ccs.neu.edu/research/demeter/DemeterJavawww.ccs.neu.edu/research/demeter/DJwww.aspectj.orgwww.aosd.net

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Static Scattering and Tanglingaspecti is scattered across many classes (i = 1,2,3)class X tangles aspects 1, 2 and 3aspect1aspect2aspect3class A consistingof three aspectsclasses foraspect1classes foraspect2classes foraspect3Class Xclass diagramAdding to classes

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Dynamic Scattering and Tanglingprogram executioninvolving three aspects (colors r b g)program call tree(objectsexecuting method calls)Each aspect (colors) is scattered across many classes (shapes)Class tangles all three aspects At those calls the aspect enhances the behaviorclassesthis(s)target(t)f(..)Enhancing callst.f(..);

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subcomputation = join points related to traversing through the objectsguided by traversal specification and class graph.

AspectJ

DJ

Kind

Dynamic

Dynamic

On What

Dynamic call graph of base program

Dynamic call graph of a subcomputation of base program

When

Pointcuts

Signatures of visitor methods

What

Before / around / after advice

Before / around / after visitor method body

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Pointcutset of execution points of any method, rich set of primitive pointcuts: this, target, call, + set operationswhere to enhanceAdvicehow to enhanceVisitor method sig.set of execution points of traversalsspecialized for traversals (nodes, edges)where to enhanceVisitor method bodieshow to enhanceDJAspectJFrom DJ to AspectJ