1 An Aspect-oriented Weaving Mechanism Based on Component-and-Connector Architecture Naoyasu Ubayashi (Kyushu Institute of Technology) February 12, 2008 Naoyasu Ubayashi, Akihiro Sakai, and Tetsuo Tamai, “An Aspect-oriented Weaving Mechanism Based on Component-and-Connector Architecture”, In ASE’07, pp

POSL Research Group  Aspect-oriented programming  Reflection  Coordination language  Modeling language  Architecture description language (ADL)  Domain-specific language (DSL)  Formal methods 2 Principles of Software Languages

Recent publications  CAiSE 2009 (21st International Conference on Advanced Information Systems) Naoyasu Ubayashi, Genya Otsubo, Kazuhide Noda, and Jun Yoshida: An Extensible Aspect-oriented Modeling Environment (to appear).  ICST 2008 (1st IEEE International Conference on Software Testing, Verification, and Validation) Naoyasu Ubayashi, Jinji Piao, Suguru Shinotsuka, and Tetsuo Tamai: Contract- based Verification for Aspect-oriented Refactoring.  ASE 2007 (22nd IEEE/ACM International Conference on Automated Software Engineering) Naoyasu Ubayashi, Akihiro Sakai, and Tetsuo Tamai: An Aspect-oriented Weaving Mechanism Based on Component-and-Connector Architecture.  ASE 2005 (20th IEEE/ACM International Conference on Automated Software Engineering) Naoyasu Ubayashi, Genki Moriyama, Hidehiko Masuhara, and Tetsuo Tamai: A Parameterized Interpreter for Modeling Different AOP Mechanisms.  ICSE 2005 (27th IEEE/ACM International Conference on Software Engineering) Tetsuo Tamai, Naoyasu Ubayashi, and Ryoichi Ichiyama: An Adaptive Object Model with Dynamic Role Binding. 3

My talk  ASE’07 + Current work 4

5 Aspect-oriented Programming AOP is a programming paradigm in which crosscutting concerns are modularized as aspects. Display updating after (FigureElement fe): (call(void set*(..)) && target(fe) { fe.display.update(fe); } advice pointcut AspectJ Problem A concern considered crosscutting in one situation might be primary in others. It is not desirable to fix a certain concern as either primary or crosscutting. It is not easy to understand software architecture (the overall behavior of a woven program). Problem A concern considered crosscutting in one situation might be primary in others. It is not desirable to fix a certain concern as either primary or crosscutting. It is not easy to understand software architecture (the overall behavior of a woven program).

6 Our research  We provide a new weaving mechanism based on component- and-connector architecture.  We propose a new interface mechanism called Weaving-interface.  We provide a new AOP language called ccJava. ccJava: Class-based Crosscutting language for Java

7 Image of our idea Concern Component (class) Concern Component (class) Concern Component (class) Concern Component (class) weaving I/F connector weaving I/F Concern weaving by connectors Contribution Proposal of Component-based AOP Architectural AOP Towards MDD Our approach is effective for software modularity, evolution, and reuse. Contribution Proposal of Component-based AOP Architectural AOP Towards MDD Our approach is effective for software modularity, evolution, and reuse.

8 Outline 1. Motivation 2. Weaving-interface & ccJava 3. Example programs 4. Implementation 5. Conclusion & Current work

9 1. Motivation

10 Interface in OOP  A client of a class has only to be aware of methods exposed by an interface of the class.  A class can be modified without being aware of the client if the class does not change the interface. client of a class component (class) programmer component (class) programmer interface

11 However, in AOP …  It is not necessarily easy for a programmer to understand the overall behavior of a woven program because a weaving modifies the behavior of a method defined in a class.

12 Our approach – Weaving-interface  A programmer who defines a weaving has only to be aware of weaving- interfaces.  A programmer of the class can change its implementation without being aware of the client if the class conforms to its weaving-interfaces. programmer who connects components component (class) programmer component (class) programmer weaving-interface Component Connector Concern Component (class) Concern Component (class) Concern Component (class) Concern Component (class) weaving I/F connector weaving I/F Component-based AOP Architectural AOP

13 Related work  AAIF: Aspect-aware interface [Kiczales 2005]  Open modules [Aldrich 2005]  Crosscutting programming interface (XPI) [Sullivan 2005] An interface is determined only once the complete system is known Point implements FigureElement void setX(int): DisplayUpdating - after returning DisplayUpdating.change(); Aspects can be woven to only exposed program points. Open modules support crosscutting within only one class. An interface for specifying rules for designing aspects and classes public aspect XPointChange { /* The purpose of … */ pointcut change(): execution(void Point.setX(int)) || … } Our Approach Software Architecture !! Our Approach Software Architecture !!

14 2. Weaving-interface & ccJava

15 Example --- Figure editor interface Shape { public void moveBy(int dx, int dy); } class Point implements Shape { int x, y; public int getX() { return x; } public int getY() { return y; } public void setX(int x) { this.x = x; } public void setY(int y) { this.y = y; } public void moveBy(int dx, int dy) { x += dx; y += dy; } class Line implements Shape { Point p1, p2; public Point getP1() { return p1; } public Point getP2() { return p2; } public void setP1(Point p1) { this.p1 = p1; } public void setP2(Point p2) { this.p2 = p2; } public void moveBy(int dx, int dy) { p1.x += dx; p1.y += dy; p2.x += dx; p2.y += dy; } class Display { public static void update() { /* the detail is ommited */ } } Three concern components are woven together by component and connector architecture based on weaving- interface. Component

16 AO weaving based on component-connector architecture class Display class Point class Line class Logging wDisplaywPointwLine wLogging redraw + change Component Weaving-interface Connector class Point implements Shape { int x, y; public int getX() { return x; } public int getY() { return y; } public void setX(int x) { this.x = x; } public void setY(int y) { this.y = y; } public void moveBy(int dx, int dy) { x += dx; y += dy; } change redraw class Display { public static void update() { } }

17 Weaving-interface in ccJava public w_interface wPoint { pointcut change(): execution(void setX(int)) || execution(void setY(int)) || execution(void moveBy(int, int)); import before(), after() returning, around() : change(); } public w_interface wLine { pointcut change(): execution(void setP1(Point)) || execution(void setP2(Point)) || execution(void moveBy(int, int)); import before(), after() returning, around() : change(); } public w_interface wDisplay { pointcut redraw(): execution(void update()); import before(), after() returning : redraw(); export redraw(); } weave { class Pointimplements wPoint; class Lineimplements wLine; class Displayimplements wDisplay; connect (port1:wDisplay.redraw, port2:{wPoint || wLine}.change) { after() returning : port2 { port1.proceed(); } } ccJava: Class-based Crosscutting language for Java Connector Port Definition Port Connection Coordination Code Weaving-interface Coordination Type Before After Around introduce Connector descriptions depend on only weaving-interfaces. Architecture can be represented by Weaving-interface + connector. Weaving-interface+Connector is a kind of ADL (Architecture Description Language) Weaving-interface+Connector is a kind of ADL (Architecture Description Language)

18 3. Example programs

19 Example (1) --- Method composition public w_interface wColor { pointcut change() : execution(void setColor(int)); export change(); } public w_interface wPoint { pointcut change(): execution(void setX(int)) || execution(void setY(int)) || execution(void moveBy(int, int)); import before(), after() returning, around() : change(); } weave { class Colorimplements wColor; class Pointimplements wPoint; connect(port1:wColor.change, port2:wPoint.change){ around() : port2 { port2.proceed(); port1.proceed();}} } Weaving-interface Connector Color setColor Point setX setY moveBy behavioral composition Component

20 Example (2) --- Class composition (Inter-type declaration) public w_interface wColor { pointcut color_property() : field(int color) || method(void setColor(int))|| method(int getColor()); export color_property(); } public w_interface wColorPoint extends wPoint { pointcut thisClass() : class(this); import introduce() : thisClass(); } weave { class Colorimplements wColor; class Pointimplements wColorPoint; connect(port1:wColor.color_property, port2:wColorPoint.thisClass) { introduce() : port2 from port1; } } Weaving-interface Connector Color setColor getColor Point setX setY moveBy structural composition Component color Point setX setY moveBy setColor getColor color

21 Example (3) --- Software evolution with ccJava class Point implements Shape { int x, y; public int getX() { return x; } public int getY() { return y; } public void setX(int x) { this.x = x; } public void setY(int y) { this.y = y; } public void moveByPlus (int dx, int dy) { x += dx; y += dy; } weave { class Pointimplements wPoint replacing moveBy with moveByPlus; class Lineimplements wLine; class Displayimplements wDisplay; connect(port1:wDisplay.redraw, port2:{wPoint || wLine}.change){ after() returning : port2 { port1.proceed();}} } class Point implements Shape { int x, y; public int getX() { return x; } public int getY() { return y; } public void setX(int x) { this.x = x; } public void setY(int y) { this.y = y; } public void moveBy(int dx, int dy) { x += dx; y += dy; } version 1version 2 Component Connector Weaving-interfaces do not have to be modified ! Renaming

22 Example (4) --- Interface for dealing with multiple classes public w_interface wChange { pointcut change(): execution(void set*(..)) || execution(void moveBy(int, int)); import before(), after() returning, around() : change(); } weave { class Pointimplements wChange; class Lineimplements wChange; class Displayimplements wDisplay; connect(port1:wDisplay.redraw, port2:wChange.change){ after() returning : port2 { port1.proceed(); } } } The scope of the weaving impact is limited to classes that implement wChange. We have only to look at Point and Line. Weaving-interface Connector class Point implements Shape { int x, y; public int getX() { return x; } public int getY() { return y; } public void setX(int x) { this.x = x; } public void setY(int y) { this.y = y; } public void moveBy(int dx, int dy) { x += dx; y += dy; }

23 Evaluation: Expressiveness for crosscutting descriptions NAWNOCNOC/NAW AspectJ (AAIF)122 ccJava as an open module221 ccJava using wildcard122 NAW: number of aspects or weaving-interfaces NOC: number of classes (Point, Line) wPoint wLine wChange Good Weak Good DisplayUpdating Cannot crosscut multiple classes Can crosscut multiple classes

24 Evaluation: Traceability of weaving impact NOCIFWNOIF AspectJ1all aspectsnumber of aspects AAIF1AAIF1 ccJava1weaving-I/Fsnumber of weaving-IFs NOC: number of classes IFW: impact factors for weaving NOIF: number of impact factors number of all aspects > number of implemented weaving-IFs Weak Good Linguistic reasoning is difficult Linguistic reasoning is easy

25 4. Implementation

26 Compiler construction ccJava code (weaving-interface) Java code (class) ccJava parser AspectJ code generator AspectJ code (aspect) Aspect-Factory class generator AspectJ weaver executable program ccJava compiler

27 Generated code aspect wPoint { Display display = new DisplayFactory. getInstance(); pointcut change(): execution(void Point.setX(int)) || execution(void Point.setY(int)) || execution(void Point.moveBy(int, int)); after() returning: change() { display.update(); } } public class DisplayFactory { private static Display instance = new Display(); public static Display getInstance { return instance; } generated aspect generated factory class weave { class Display implements wDisplay factory UserDefinedFactory; /* other definitions are omitted */ } If a programmer wants to define a specific factory class, …

Verifiable AO MDD Not only programming-level but also design-level notion ADL for bridging a gap between architectural design and implementation 28 Architectural Design Weaving-interface Java Designs and verifies an architecture represented by a set of weaving-interfaces (Alloy-based architecture verification) Implements verified weaving interfaces

ccModeler & ccJava 29 Architectural Design Weaving-interface Java ccModeler ccJava Designs and verifies an architecture represented by a set of weaving- interfaces Implements verified weaving interfaces Architecture Design & verification Refinement

30 6. Conclusion & Current ongoing work

31 Conclusion  A new interface mechanism Weaving-interface  A new weaving mechanism based on component-and-connector architecture Flexible Weaving Mechanism !

Current work -- From Weaving-interface to Archface  Archface: architectural interface for bridging a gap between design modeling and implementation  Archface integrates not only design modeling with its implementation but also AO with OO. 32

Example: Observer Pattern 33 Archface Implementation In archface, a collaborative architecture is specified by a set of ports based on the pointcut mechanism. Pointcut-based interface