ModTransf A Simple Model to Model Transformation Engine

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ModTransfA Simple Model to Model Transformation
Engine

• Cédric Dumoulin

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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

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Proposed Solution
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Proposed Solution

• A transformation engine
• takes model(s) and set of rules as input,
• and produce model(s)

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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

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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.

r1
r2
r3
r4
r5
T
input MM
output MM
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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

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Rule Example 1 (UML)
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Rule Example 1(XML)
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Rule Example 2 (UML)Nested Concept
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Rule Example 2 (XML)
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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

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Transformation (UML and XML)
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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

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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

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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

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Advanced Features
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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

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Extra Properties Usage
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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)
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Code Generation Example
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Documentations
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• Ongoing effort
• Schema
• modtransf-v3
• XML syntax

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XML Rule SyntaxSchema (transformation)
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XML Rule SyntaxSchema (domains)
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Access To Models

• Throw a common API
• Should be implemented for each Technology
• JMI, XML, EMF, Database,

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Models Kind

• 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

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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

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Questions and Discussion
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