Contribution to Generative Programming

Application into the SmartTools generator: XML technologies, aspect-oriented

programming and components

Carine CourbisINRIA Sophia-Antipolis

UCL - Software Systems Engineering Group (London)BTexact Technologies (Adastral Park, Ipswich)

31st March/1st April 2003

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Context of this WorkINRIA Sophia-Antipolis, OASIS team SmartTools Project (http://www-sop.inria.fr/oasis/SmartTools)

Contracts: Bull Cp8, Microsoft and W3C Pragmatic developments

5 Members:– 1 Research Scientist: Dr. Didier Parigot [INRIA Sophia-Antipolis]

– 3 Research Engineers: Pascal Degenne [now CIRAD],

Alexandre Fau [now Ilog R&D],

Dr. Claude Pasquier [now CNRS]

– 1 PhD Candidate: myself

This talk = my PhD defence talk

Questions, at anytime, welcomed

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Context: Upheaval Factors [1/3]

Changes in Computer Science due to:– The Internet

From PC-enclosed applications to Distributed ones

Communication between applications and users data exchange format ? XML Standard from W3C

– Proliferation of new TechnologiesMany solutions to a problem (e.g. component)

Which one to choose ? The more Perennial ?

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Context: Upheaval Factors [2/3]

– Democratisation of Computers Spread on none-technical domains

Different knowledge, needs, supports, activity domains

– Pressure of the market, CompetitionDevelopments: quicker, cheaper, adaptable

New Methods to Develop Applications Evolutionary Software, Adaptable to Needs

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Context: Development Techniques [3/3]

Programming LevelOOP: encapsulation, inheritance code

extensible, reusable, modular, but … Cross-cutting Concerns, Mixing of Functional/None-

Functional code

AOP, SOP, Intentional Programming

Component Programming, etc.

Specification LevelDocument format Standardisation (W3C)

UML, MDA of OMG

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Objective and ApproachTo propose a new way of programming using

code generation [Czarnacki, Eisenecker] from Models

To integrate Technologies/Needs at generation MDA

Benefits: adaptable code to Technologies and Needs, to focus only on the "intelligent" part (ease programming)

Additionally: Use of Standards from W3C and OMG

(Tools and Evolutions)

Generation /Transformations

CodeModel

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MDA ApproachMDA: Model-Driven Architecture of the OMG [Bézivin]

Platform (Technology) Independent Model

Platform (Technology) Specific Model

To have a UML Domain-specific Model and to Specialise it by Transformation

Our Approach: MDA but at Different Levels and with Languages

EJB

ComponentModel

CCMWeb-Services

Generation /Transformations

PIM

Example:

PSMPSMPSM

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Instantiation, at different levels, in SmartTools

SmartTools = Software Framework To help developing DSLs/Tools

Default Visitor + AOP

For a Language L

Component Model

Pretty-printerParser

Specification

Components

SmartToolsGenerato

rs

Data Manipulation

API DTD or XMLSchema

StructuredEditor

PSM

Data Model

PIM

SemanticAnalysesModel

View/GUI Model

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Plan

Subject SyntacticTools

SemanticTools

Architecture Conclusion

AbSyntBridge DTD

CoSynt

AOP

Visitor

ConfigurableVisitors

DecoupledVisitors

Context

Projection

Approach

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XML Document Java Objects

Our DataModel /Algebra

Java Classesabove DOMgenerate

convertDTD

orXML Schema translate

Open to Document world: Bridge

can be serialised inXML Document

is conform to

is represented byObjects/Nodes

is instance of

Possible Semantic Analyses

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Views/GUI Model: CoSynt

Goal: To Transform an AST into a graphical/text viewHigh Level Language, Separation of Concerns

Generation : Pretty-printer and the associated Parser• Concrete Syntax • Display (sequences of transformations)

AST

Tree of graphical objects

Textual form

Tree of objectswith styles

Concrete Syntax Tree

Specialisation/Refinement by successive Transformations

ast sugars, ast

boxes,ast, sugars

styles, boxes,

ast, sugars

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CoSynt Parser, Pretty-printer (using Standards)

+

assign(Var var, Exp e)AbSynt

Concrete Syntax {assign(v,e) : v "=" e ";"}Layout {assign : line:(1 2 3 4)

BML Nlabel : var, intText newline : assign}

CoSynt

ANTLR Specification

XSLT stylesheet (text)

XSLT stylesheet (view)

Text

BML File

Swing Objects

+ CSSSwing Objets

with styles(view isomorphic to the AST)

AST+

LL(k) Parser in Java

Benefit from Standard Tools

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Plan

Subject Syntactic Tools

SemanticsTools

Architecture Conclusion

AbSyntBridge DTD

CoSynt

AOP

Visitor

Configurable Visitors

DecoupledVisitors

Context

Projection

Approach

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Aspect-Oriented Programming

To Modular concerns and to interleave (weave) them , when requested, into the class code

Where to weave?

How to compose many aspects?

Which implementation technique to choose?

Separation of concerns [Kiczales]

Aspects

CodeWeaver

Classes

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Design Pattern Visitor in Java

To define Operations on Objects Structure (tree)

– Without Modifying the Objects

– Code (extensible module) and Structure Separation

class Visitor1 implements Visitor {

void visit(T1 node) { ...

node.getSon().accept(this);

}

void visit(T2 node) {…}

void visit(T3 node) {…}

}

static type dynamic type

class Visitor2 extends Visitor1 {…}

class T2 implements I2 { void accept(Visitor v) { v.visit(this); }...

class T1 …

class T3…

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1st Solution: Configurable Visitors

Goal: ”To hide" the Visitor design pattern (in Java) Natural and Extensible CodeDrawbacks: accept, fixed parameters and return type of

methods casts or global variables

Solution: From model, Visitor Generation• Pre-computation to statically look for methods• Visit methods with configurable signatures and traversal• Aspects dedicated to our Visitors (more extensible

analyses), statically or dynamically plugged in

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2nd solution : Decoupled Visitors

Goal: Reuse the Analyses Composition, EnrichmentSeparation: Structure, Traversal, Semantic Actions

a Visit = n pieces of code Aspects

before, after, and between the sons

Visitor = Code Weaver (~ Attribute Grammar evaluator)

public Object beforeOp(AffectNode n, Object p) {…}public Object betweenElem1and2(AffectNode n, Object p) {…}public Object afterOp(AffectNode n, Object p) {…}

visit(){ before visit() between visit() after}

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Subject SyntacticTools

SemanticTools

Architecture Conclusion

AbSyntBridge DTD

CoSynt

AOP

Visitor

ConfigurableVisitors

DecoupledVisitors

Context

Projection

Approach

Plan

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Architecture : Context

SmartTools : To Generate autonomous Tools (Services) for DSLs + Meta-tool (generic tool)

Goals : Tools Exportation and Importation + Architecture Configuration depending ApplicationObjects are too fine-grain Components

• Specification of Required Interfaces (dependence)• Deployment

Componentspecification

LaunchingspecificationContainer

Component

Functional

Façade

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Architecture : Our Approach

Which component technology to choose? Solution: MDA approach

PIM: own abstract component model

PSMs: SmartTools, EJB, CCM, Web-Services

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Architecture : Projections<component name="graph" extends="abstractContainer"> <containerclass name="GraphContainer"/> <facadeclass name="GraphFacade"/> <input name="addNode" method="addNode"> <parameter name="nodeName" javatype="java.lang.String">... </input> </component>

Container class+

Extension façadeclass

SmartTools

WSDL file+

SOAP corresponding

class

Web-Services

IDL File+

CORBAserverclass

CCM

Remote andHome

Interfaces

EJB

Component specification

?

Eclipse

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Subject SyntacticTools

SemanticTools

Architecture Conclusion

AbSyntBridge DTD

CoSynt

AOP

Visitor

ConfigurableVisitors

DecoupledVisitors

Context

Projection

Approach

Plan

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Results : Utilisation examples

SmartTools Internal Languages (bootstraps)AbSynt, CoSynt, ViProfile, CDML (component)

W3C LanguagesXSLT, SVG, DTD, XML Schema, CSS, XML

Programming Languages or DSLjava, ant, etc. (because of XML bridge)

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Conclusion

Data AbSynt

Domain-specific part (PIM)

Generated Targets(PSM)

Java classes above DOM,DTD/XML Schema

View/GUI AbSynt + CoSynt Pretty-printer, Parser

Sémantics AbSynt + ViProfile Visitors in Java

Components CDMLComponents for SmartTools,EJB, CCM or Web-Services

Technology/LanguageIndependent

Model

Generation /Transformations

Code enriched withTechnologies

Approach MDA

Generative programming: evolutionary software, applicable to levels

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Research Perspectives [1/2]

Semantic analyses: – Composition rules of Semantic Actions– To make language components ~ GenVoca [Batory]

– Pattern-matching: JDOM [Moreau, Kirchner], Pizza [Odersky], Java 1.5?

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Research Perspectives [2/2]

Components: – To Add the possibility of Aspects inside

Objects + Aspects = Components– To Model the projection mechanisms

Abstract PIM Application PIM PSMsSmartTools: Experimentation platform

Bridges toward other Worlds:– Semantic-Web: Abstract Syntax RDFS– UML: Abstract Syntax MOF

Quick Demo

Contribution to Generative Programming

Application into the SmartTools generator: XML technologies, aspect-oriented

programming and components

Questions ...

http://www-sop.inria.fr/oasis/SmartTools

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Data Model (Algebra): AbSynt

Program AST (Abstract Syntax Tree)

Why a new Formalism ?• To have a High Level Structuring Description format,

independent technology/language• To accept DTD/XML Schema Optional/List Son• To have an Abstraction towards the Implementation

layer to manipulate nodes

<assign> <var>a</var> <int>2</int></assign>

a=2;

assignvar int

"a" "2"or

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PIM: Constructors (Operators), Types, Attributes, and Semantic DataPSM: Java Classes above DOM to obtain Strictly Typed Trees DOM Services: serialisation, XPath, XSL, etc.

AbSynt Java Classes above DOM

package tiny.astpublic interface AssignNode extends StatementType { public tiny.ast.VarType getVariableNode(); public void setVariableNode(tiny.ast.VarType node); ...

Statement = assign(Var variable, Exp value);Required env as java.lang.String in affect;vector as java.util.HashMap in affect;

Type Interface, Constructor Interface + ClassAttribute Variable

Generated Code

Written Code Transformation(SmartTools)

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Abstract Syntax versus DTD, XML Schema

Analogies– Constructors = Elements, Attributes = Attributes– Types some of the parameter Entities, choices, substitutable

elements ( type notion of XML Schema, corresponding to content model)

Differences/Difficulties– Optional/List son notion

– EBNF description: content model sometimes too complex Loss of structure information

<!ELEMENT el (op1, (op2|(op3, op4)|(op5, op6*)))> el(T1 f1, T2[] f2); with T1=op1; et T2= op2, op3, op4, op5, op6;

Example

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ViProfile Configurable Visitor (Java)

+assign(Var var, Exp e)AbSynt

Integer visitSt(%Statement, Type t);String visit(%Var, Type t);

ViProfile

abstract class AbstractVisitor extends ClassicVisitorImpl { void pre-computation() {...} ...

class TraversalVisitor extends AbstractVisitor {…}

class Visitor extends TraversalVisitor { Integer visitSt(AssignNode node, Type t) { String s = visit(node.getVar(), t);...

class TraceAspect implements Aspect { public void before(Type t, Object[] p) { System.out.println(”before " + p[0]); } public void after(Type t, Object[] p) {}

}

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Running Example of a Decoupled Visitor

Decoupled Visitor~ Code Weaver

Dynamic Traversal

S1 Action

S2 Action

S3 Action

S4 Action

1] traverse()

2] beforeOp(UntypedNode)

4]

5]

6]

3] beforeOp(AssignNode, Object)

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Comparison between the two Solutions

Same expression power– 1st: natural (thank to code generation) and extensible

code but no reusable

– 2nd: reusable code but less readableExample: a typechecking analysis was enriched

with an initialisation variable check

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Views/GUI Model: CoSynt

Goal: To Transform an AST into a graphical/text viewHigh Level Language, Separation of Concerns

Generation : Pretty-printer and the associated Parser• Concrete Syntax • Display (sequences of transformations)

assignvar int

"a" "2"

AST

Nboxassign

Sboxline

Nlabelvar

"a"Slabel

keyword

"="Nlabel

int

"2"Sbox

keyword

";"

Tree of graphicalobjects

a=2; Textual form

Tree of objectswith styles

assign

var int

"a" "2"

"=" ";"

Concrete Syntax Tree

Specialisation/Refinement by successive Transformations