a verification mechanism for weaving in extensible aom languages

POSL (Principles of Software Languages) Gr.Kyushu Institute of Technology, Japan

http://posl.minnie.ai.kyutech.ac.jp/

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A Verification Mechanismfor Weaving in Extensible AOM

Languages

Naoyasu Ubayashi, Yusaku Maeno, Kazuhide Noda and Genya Otsubo

ADI2007 @ ECOOP2007

July 30, 2007

POSLposl.minnie.ai.kyutech.ac.jp

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Outline Motivation AspectM: an extensible AOM language Verification mechanism Conclusion


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1. Motivation


Extensible AOM language AOM (Aspect-oriented Modeling)

languages can cope with concerns at the early stages of the software development phases.

We previously proposed a UML-based AOM language called AspectM.

AspectM is an extensible AOML based on MMAP (Metamodel Access Protocol).

The extension mechanism in AspectM is effective for constructing domain-specific modeling languages.

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Problems in extensible AOM languages

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Extensible AOM LanguageA modeler can extend metamodel.A modeler can add new aspects that include user-defined JPMs.(user-defined pointcuts, etc)

Does a pointcut

select join points

correctly ?

Does a base

model conform to metamodel

?

Does a woven model include cyclic

inheritances?

It is not necessarily easy to check model consistency and aspect interference.

Verification mechanism


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2. AspectM: an extensible AOM language


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AspectM

AspectM JPM の簡易表も載せる

JPM Join point Advice

PA (Pointcut & Advice) operation before, after, around

CM (Composition) class merge-by-name

NE (New Element) class diagram add/delete-class

OC (Open Class) class add/delete-attribute, add/delete-operation

RN (Rename) class, attribute, operation rename

RL (Rlation) class add/delete-relationship, add/delete-aggregation

IH (Inheritance) class add/delete-inheritance

Pointcut cname(‘Customer’) || cname(‘Invoice’)

Aspect name : Logging

Advice Join Point Type : Open Class Add “log()”method to join point


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There might be situations in which a modeler wants to introduce domain-specific notations and JPMs.

AspectM is nice, but …

pointcut-body := !DCEntityContract_UniqueId_isUserAssigned(*)advice-body := <<DCLoggerOperation>>log()

{isUserAssigned=false}

{isUserAssigned=false}

{isUserAssigned=true}


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AspectM extension mechanism

AspectM metamodel

AspectM model

introducea new kind of

domain-specificmodel element

modifythe AspectMmetamodel

reflect

reify

MMAP

extensionpoint

new modelelement

protocols

Reflective Model Editor

Base levelBase level

Meta levelMeta level

Editing-timestructuralreflection

DSLComponents


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MMAP

Extension pointsClass, Attribute, OperationPA, CM, NE, OC, RN, RL, IH

Extension operationsdefine subclassesadd attributes to

subclassescreate associations

among subclassesadd constraints using

OCLPrimitive predicatespredicates for navigating

the AspectM metamodel

AspectM metamodelClass Element

Aspect Element

extension point example of extension operations


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Metamodel navigation

DCEntityContract_UniqueId_isUserAssigned (c): meta-class-of ("DCEntityContract", c) && member-of (a, c) && meta-class-of ("UniqueId", a) && member-of ("isUserAssigned", "UniqueId") && value-of ("true", "isUserAssigned")

DCEntityContract_UniqueId_isUserAssigned (c): meta-class-of ("DCEntityContract", c) && member-of (a, c) && meta-class-of ("UniqueId", a) && member-of ("isUserAssigned", "UniqueId") && value-of ("true", "isUserAssigned")

meta-class-of

member-of

meta-class-of

member-of

value-ofBase level

Meta level


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Overview of Reflective Model EditorDemonstration

Base Editor

Meta Editor

1. Execute extension operations

2. Assign a graphic notation to a new model element

3. Regenerate the metamodel

4. Restart the base editor

Extension Procedure

Base Editor

Invoke the Meta Editor

14Meta Editor

Show an extension point

Create a new metaclass

Rebuild the Base Editor

Assign a graphic notation

Execute extension operations(add attribute, association, …)

Add a constraint using OCL

A class can have at most one UniqueId.

self.owner.feature ->select(oclIsTypeOf(UniqueId))->size() <= 1

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New model elements are added to the pallet

Base Editor

This violates the constraint

A class can have at most one UniqueId.

self.owner.feature ->select(oclIsTypeOf(UniqueId))->size() <= 1

Base Editor can detect this error

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Base Editor

Meta Editor

　　 Reusable DSL component


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3. Verification mechanism


What should be checked ? Structural correctness (Syntax check) Intention of a modeler (Semantic check)

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[Syntax Check] Structural correctness Consistency between base models and

metamodel– Base models might not conform to metamodel if it evolves

(metamodel can be modified by a modeler).– A woven model might not conform to metamodel even if

each base model before weaving conforms to metamodel (aspects can be added by a modeler).

– A woven model might include inference including name conflicts, multiple inheritance and cyclic inheritance.

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ExtendedMetamodel

V1

checkconformance

ExtendedMetamodel

V2

Base model

Woven model

ExtendedMetamodel

evolution(introduce

new elements)

weaving

checkconformance

&inference


Model structure checker

1. Generate a default schema from the original metamodel.

2. Check whether the metamodel is extended.3. Redefine the schema if extended.4. Check whether a base model conforms to the

extended metamodel.

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1 :<xsd:complexType name="ClassType"> 2 : <xsd:choice maxOccurs="unbounded" minOccurs="0"> 3 : <xsd:element name="Attribute" type="AttributeType"/> 4 : <xsd:element name="Operation" type="OperationType"/> 5 : <xsd:element name=“TransactionOperation" type=" TransactionOperationType"/> 6 : </xsd:choice> 7 : <xsd:attribute name="name" type="Name" use="required"/> 8 : <xsd:attribute name="isAbstract" type="Boolean" use="optional"/> 9 : </xsd:complexType>10 :11 : <xsd:complexType name=" TransactionOperationType ">12 : <xsd:complexContent>13 : <xsd:extension base=“OperationType“/>14 : </xsd:complexContent>15 : </xsd:complexType>

POSLposl.minnie.ai.kyutech.ac.jp[Semantic Check] Intention of a

modeler Assertions for checking (un)favorable

properties– Captured join points might not be the points intended

by a modeler.– Intended results might not be obtained when a modeler

makes a mistake in specifying the precedence.– The mixture of illegal pointcut designators and illegal

aspect precedence might cause an unexpected weaving.

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Woven model

checkassertions

Assertionssuper_class_of (c1, c2)attribute_of (a, c)operation_of (o, c)advice_of (a, o)class_exist (c)related_to (c1, c2)aggregate(c1, c2)composed_of (c1, c2)

specifiedby predicates

base and meta modelscan be navigated using predicates


Assertion checker1. Translate base and meta models into Prolog facts.2. Generate Prolog queries from assertions.3. Check the satisfiability.

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A model represented in XML<ownedElement name="TransOp" xsi:type="asm:TransactionOperation" />

Prolog factsmodelElement( [property('tagName', 'ownedElement'), property('name', 'TransOp'), property('xsi:type', 'asm:TransactionOperation')])

Assertionoperation_of ('TransOp', 'C')

Translate

Check

Assertion for checking the effect of a single aspect can be automatically generated.


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4. Conclusion


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Conclusion & Future work

We clarified how the metamodel extension affects the verification of the weaving.

We proposed a verification mechanism for weaving in extensible AOM languages.

Currently, only simple cases are shown. We must prepare verification mechanisms corresponding to the

purpose of AO modeling (Behavior modification, Refinement (MDA) …)

Constraints specified in metamodel can be useful for verifying a weaving.


Constraint preservation In AspectM, pre-/post-conditions and invariants

can be specified for rigorous modeling. However, a weaving might break the constraint

specified in a model before weaving.

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What kind of weaving should be allowed ?

For example, behavior subtyping ( MDA, … ), and so on.

A first step towards verifying model weaver


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Appendix


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Base Editor

Implementation (1) -- Reflective model editor

Metamodel for EMF

Map model for GMF

Tool model for GMF

Graph model for GMF

Code Generator for EMF

Code Generator for GMF

Code ofModel Editor

Code ofGraphic Editor

Eclipse Modeling Framework

Graphical Modeling Framework

Extended Metamodel

Interface

Graphic Editor Generator

Modeler

Meta Editor

Core Editor Generator


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Implementation (2) -- Model weaver

Base Editor

ModelerProlog

Non WovenModel

Fact

write

convert

WovenModel

Weaving

Model Weaver

analyze pointcut

Model Editor

a verification mechanism for weaving in extensible aom languages

Documents

extended metamodel

original metamodel

metamodel aspects

base editorassign

base editor meta

new model elements

modeler semantic

cyclic inheritance