ModTransf A Simple Model to Model Transformation Engine Cédric Dumoulin

Requirements Model input: XMI files, ruled by a MOF metamodel XML files, ruled by an XML schema Easy maintenance of transformation rules To follow metamodel changes Code generation from model Simple to use Yet available

Proposed Solution

A transformation engine takes model(s) and set of rules as input, and produce model(s) rules model rules transformation engine MM based on instance of

Vocabulary Model: Graph of related Concepts Concepts defined in metamodel Metamodel (MM): Graph of classes defining concepts Transformation Specify how concepts from input MM are mapped to concepts of output MM

Basic Principle “Divide and Conquer” Express transformation rule by rule Rule Specify how one or few input concepts are transformed to one or few output concepts. input MMoutput MM T r1 r2 r3 r5 r4

Rule A rule is made of: domains describe input and output concepts can contain complex conditions implicitly define enterGuard, exitGuard, concept creations implicitly define rule parameters enterGuard to guard the rule execution actions to populate concept, perform code generation, do additional computation, … exitGuard to check the result bind variables to bind concept and properties to guards and actions

Rule Example 1 (UML)

Rule Example 1(XML)

Rule Example 2 (UML) Nested Concept

Rule Example 2 (XML)

Transformation A transformation is made of: involved models declaration rules topRule  called by the engine  execute all possible solutions on input domains rule  called by other rules selectRule  set of rules called by other rules  the first matching rule is executed

Transformation (UML and XML)

How Transformation is Processed Called with input and output models Specify which models are used as target target models are usually empty models are bind to transformation model names TopRules are executed input domains are those referring to input models output domains are those referring to output models

How Rules are Processed Input bind variables are set Input enter guards are checked stop if not verified Output actions are executed Output objects are created and populated starting from the more nested one (leafs) For a concept, property values are computed first, then the object is created and populated. Output post actions are executed Output exit guards are checked

Multiple Call of a Rule Call of a rule with the same set of parameters Return the same result Only the first call is executed Subsequent calls return the first result  multiple properties referencing the same concept are transformed to references to the same transformed concept

Advanced Features

Extra Properties Definition (ex: stereotypes) Extra Properties can be defined on model concepts Usage like regular properties Only visible in the transformation Example definition of the property “stereotypes” used to check stereotype defined by the model helper

Extra Properties Usage

Code Generation Associate code templates to rules Templates contain Replacement places for attributes Nested rule calls Use Velocity templates $c1.packageName #foreach( $import in $c1.import ) import $import; #end public class ${c1.name} { // attributes $engine.callRule("attribute“, “src.feature“) // methods $engine. callRule( “method”, “src.method”) }

Code Generation: Example

Documentations

Ongoing effort Schema modtransf-v3 XML syntax

XML Rule Syntax: Schema (transformation)

XML Rule Syntax: Schema (domains)

Access To Models Throw a common API Should be implemented for each Technology: JMI, XML, EMF, Database, …

Engine takes graphs of objects as models Model loading is not part of the engine Can use JMI, JAXB, Castor, DOM, … From MOF metamodel: Use JMI From XML schema Use JAXB, Castor Models Kind XMI model MOF metamodel JMI classes JMI import/ export generate XML model schema Java classes JAXB import/ export generate

Future features Aspect like property declaration enable declaration of extra properties and methods on model concepts Structure and classes declaration To create data needed during transformation dependsOn Allows specification of rule dependencies Inheritance Key declarations To lookup created concepts by specified properties …

Questions and Discussion