Sheet 1Symposium How Adaptable is MDA May 20, 2005 Enschede

Implementing Language Extensions with Model

Transformations

Ivan Kurtev

Software Engineering GroupUniversity of Twente

the Netherlands

Sheet 2Symposium How Adaptable is MDA May 20, 2005 Enschede

Outline

The Role of Languages in MDE; Language Elements; Language Extensions; Examples:

Language composition; Abstract syntax extension;

Conclusions;

Sheet 3Symposium How Adaptable is MDA May 20, 2005 Enschede

Use of Languages in MDE

Meta-modeling: modeling of languages; Transformation languages:

ComputationIndependentModel (CIM)

PlatformIndependentModel (PIM)

PlatformSpecific

Model (PSM)

Source Model Transformer Target Model

TransformationSpecification

Languages for expressing models:

Can we use MDE techniques to solve language design problems?

Sheet 4Symposium How Adaptable is MDA May 20, 2005 Enschede

Concrete Syntax Related to parsing; Textual, visual;

Abstract Syntax (L) Defines the structures represented by the concrete

syntax;

Semantics: Semantic Domain (D); Semantic Mapping (M)

M: L -> D

Language Elements

Sheet 5Symposium How Adaptable is MDA May 20, 2005 Enschede

Language Extensions

Syntax Extensions: Extensible grammars; Extensible parsers; Macro definitions;

Semantic Extensions: Modular attribute grammars; Monads; Action semantics;

Language Composition: Involves syntax and semantic extensions;

Sheet 6Symposium How Adaptable is MDA May 20, 2005 Enschede

Language Elements in MDA Terms (1)

Concrete Syntax: ? Abstract Syntax (L)

Defined as a meta-model;

Semantics: Semantic Domain (D): a model Semantic Mapping (M): a model transformation;

M: L -> D

Sheet 7Symposium How Adaptable is MDA May 20, 2005 Enschede

How can MDA techniques be used for language design tasks?

What do we gain (do we do better than the current techniques) ?

How are traditional problems solved in MDA? Language reuse; Language composition; Language extension;

Language Elements in MDA Terms (2)

Sheet 8Symposium How Adaptable is MDA May 20, 2005 Enschede

Example 1: Composing XML Languages

XMLDocument

DOMParser

ProcessingCode

DOM Tree Application Objects

Application-specific XML processing:

Transformation from XML document to application objects;

XML Language Composition: Concrete syntax composition is solved; Semantic mapping: composition of transformations; Semantic domain: software composition;

Application: hybrid XML languages and compound documents;

Transformation

Sheet 9Symposium How Adaptable is MDA May 20, 2005 Enschede

Transformation Pattern for XML Processing

Schema-less processing: based on DOM; Schema-based processing: an XML schema and DOM are available;

XML DocumentModel

ApplicationClasses

XML Document ObjectsTransformationEngine

TransformationSpecification

input output

executed by

XML SchemaModel

an XML schema

TransformationLanguage

written in

instanceOf instanceOfinstanceOf

uses usesSchemaInstOfDef

SchemaInstOf

Sheet 10Symposium How Adaptable is MDA May 20, 2005 Enschede

Structure of XML Applications

Separation of concerns: Syntax (schema); Processing logic (transformation specification); Application classes (semantic domain);

XML DocumentModel

ApplicationClasses

XML Document ObjectsTransformation

Engine

TransformationSpecification

input output

executed by

XML SchemaModel

an XML schema

TransformationLanguage

written in

instanceOf instanceOfinstanceOf

Static part of an XML application

Dynamic part of an XML application

uses uses

Sheet 11Symposium How Adaptable is MDA May 20, 2005 Enschede

Example (1)

Processing of a subset of SMIL timing module; Source schema:

<attribute name=’begin’ type=’string’/><attribute name=’end’ type=’string’/><attribute name=’dur’ type=’string’/><attribute name=’timeContainer’

type=’string’/> Example of a timed document:

<a timeContainer=’seq’ begin=’1’ dur=’20’> <b timeContainer=’par’ dur=’10’> <c timeContainer=’none’ dur=’10’/> <d timeContainer=’none’ dur=’10’/> </b> <e timeContainer=’none’ dur=’10’/></a>

SMIL – Synchronized Multimedia Integration Language

Sheet 12Symposium How Adaptable is MDA May 20, 2005 Enschede

Target Application Classes:

Example (2)

start()stop()

beginenddurctrlObject : ControlledObject

«JavaClass»TimedElement

+activate()+deactivate()

«interface»ControlledObject

«JavaClass»Interval

«JavaClass»TimeContainer

«JavaClass»Parallel

«JavaClass»Sequence

1

+components

*

Sheet 13Symposium How Adaptable is MDA May 20, 2005 Enschede

Composition of XML Languages

A new language may be composed with the timing module:

XML DocumentModel

XML Document(time constrained

widgets)

Time graph andwidget objects

TransformationEngine

executed by

XML SchemaModel

instanceOf instanceOfinstanceOf

Widget language

Timing Module

Widget Transformation

Timing Transformation

Widget Classes

Time GraphClasses

New processor is obtained via: Composing target application classes (software

composition); Composing transformation definitions (based on the

transformation language constructs);

Sheet 14Symposium How Adaptable is MDA May 20, 2005 Enschede

Example 2: Abstract Syntax Extensions

Problem: what if a transformation language does not support

required compositional operators?

Possible Solutions: Compose transformation definitions by applying a

transformation; Extend the transformation language with new constructs;

Example: Extending the abstract syntax of a language;

Sheet 15Symposium How Adaptable is MDA May 20, 2005 Enschede

Example 2: Implementation

TLMeta-ModelExt TLMeta-Model

TExt TTLTranslation

ExtensionImpl

InstanceOf InstanceOf

Extends

Executed by

Source TargetInstanceOf

Input Output

Extended syntax is transformed to the initial syntax:

Sheet 16Symposium How Adaptable is MDA May 20, 2005 Enschede

Sequential Composition of Extensions

Sheet 17Symposium How Adaptable is MDA May 20, 2005 Enschede

Conclusions

Examples of applicability of MDA techniques: Composition of XML languages; Abstract syntax extension;

Open Questions: Are model transformations suitable for defining semantic

mappings? For which type of languages? Scalability in case of language composition? Comparison to other techniques (attribute grammars,

action semantics,…)