ATLAS

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ATLAS Atlas Transformation Language

• Thiago Araújo

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Introduction

• Welcome Eclipse M2M Project
• Subproject by Eclipse Modeling Project (orthers
  EMF, GMF).
• ATLAS group LINA INRIA Nantes
• answer to the OMG MOF/QVT RFP
• ATL
• Model Transformation Language (core of MDA)?
• Toolkit ATL Integrated Environment (IDE) over
  Eclipse Platform

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ATLAS Language Transformation

• Hybrid Programming Language
• Declarative (preferred style )?
• Imperative (to ease the specification hard
  mapping)?
• ATL transformation program
• composed of rules
• Besides basics model transformation
• model querying facility
• definition of ATL libraries

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Overview MDA in ATL

• Models
• First class entities
• Model handling
• Transformation Model
• Conform to Metamodel and MetametaModel
• Defining the semantic of Models e MetaModels
• ATL engine support
• MOF 1.4
• Ecore
• ATL MetaModel
• MOF

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Overview ATL Transformation Example Author2Person
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Overview ATL

• Kind of ATL units, with .atl extension
• ATL modules
• ATL queries
• ATL libraries

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ATL Module

• Model to transformation model
• Fixed number of source and target models
• Structure
• Header
• Define name, sources and target models
• Import
• Import libraries ATL
• set Helpers
• Equivalent a java methods
• Contains
• Name, context type, return, ATL expression,
  optional set parameters
• Helpers attributes

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Rules of Modules

• Matched Rules
• Declarative form
• Keywords
• rule
• Sources, Targets
• using local variables
• from source patterns, filters
• to target models, initialization bindings
• do imperative code after initialization

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Rules of Modules

• Called Rules
• Facilities from imperative programming
• Particular type of helpers
• Opposed helpers generate target model elements
• Not include source pattern, no have from

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Module execution modes

• Normal execution mode
• Default execution
• target models differ from the source ones
• explicit specifications
• Refining execution mode
• transformations between similar models
• Element implicitly copied
• Module with keyword refine
• Actually only single sources and targets models

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Module execution semantics

• Default mode
• Tree phases
• module initialization
• matching sources
• initialization targets
• Refining mode
• too Tree phases
• Difference appears in initialization phases
• allocation and initialization implicitly
  generated

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ATL QUERY and LIBRARY

• ATL Query
• Compute primitive type from set sources models
• Generation of a textual output
• May include helpers and attributes
• ATL Library
• Define set helpers
• May include import
• Exists no default module element
• Cannot be executed independently

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ATL Language

• Based on OMG OCL
• Data types , Declarative expression
• Data Types

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Data Types Operations

• OCLType operation
• allInstances()?
• OCLAny operation
• oclIsUndefined()?
• oclIsKindOf(toclType)?
• oclIsTypeOf(toclType)?
• toString()?
• oclType()?
• asSequence(), asSet(), asBag()
• output(s String)?
• debug(s String)?
• refSetValue(name String, val oclAny)?
• refGetValue(name String)?
• refImmediateComposite()?
• refInvokeOperation(opName String, args
  Sequence)?

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ATL Module and Primitive data types

• ATL Module
• ATL unit
• single instance
• refer thisModule
• access helpers and attributes
• resolveTemp
• Primitives (based in OCL)?
• Boolean
• Integer
• Real
• String
• Additional functions for assist ATL queries
• writeTo(fileName String), println()?

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Collection Data Types

• Handler Collection of elements
• Collections
• Set, OrderedSet, Bag and Sequence
• Syntax
• collection_type(element_datatype)?
• collection_typeelements
• Common operations
• size(), includes(ooclAny), excludes(ooclAny),
  count(ooclAny), includesAll(cCollection),
  excludes(cColection), isEmpty(), notEmpty()?
• asBag(), asSequence(), asSet()?
• Sequence additional operations
• union(cCollection), flaten(), append(ooclAny),
  prepend(ooclAny)?
• insertAt(nInteger,ooclAny), subSequence(lowerIn
  teger,upperInteger)?
• a(nInteger), indexOf(ooclAny), first(),
  last(),including(ooclAny),
• excluding(o oclAny)?

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Collection's operations

• Set data type operations
• union(cCollection), intersection(cCollection),
  operator (sSet)?
• including(ooclAny), excluding(ooclAny),
  symetricDifference(sSet)?
• OrderedSet data type
• append(ooclAny), prepend(ooclAny),
  insertAt(nInteger,ooclAny)?
• subOrderedSet (lowerInteger, upperInteger),
  at(nInteger)?
• indexOf(ooclAny), first(), last()?
• union(cCollection), flatten(),
  including(ooclAny), excluding(ooclAny)?
• Bag data type operation
• Operations defined by OCL specification are nor
  available

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Iterating over Collection

• Accept Expression
• Syntax
• source-gtoperation_name(iterators body)?
• Iterative expressions
• exists(body)?
• forAll(body)?
• isUnique(body)?
• any(body)?
• one(body)?
• collect(body)?
• select(body)?
• reject(body)?
• sortedBy(body)?
• Not support multiple iterator
• Operator iterator()
• source-gtiterate(iterator, variable_declaration
  init_exp body)?

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Examples Operations on Collections

• testing whether a set contains an element Set1,
  2, 3-gtincludes(1)?
• evaluates to true
• computing the union of two sequences Sequence1,
  2, 3-union(Sequence7, 3, 5)?
• evaluates to Sequence1, 2, 3, 7, 3, 5
• flattening a sequence of sequences
  SequenceSequence1, 2, Sequence3, 5, 2,
  Sequence1-gtflatten()?
• evaluates to Sequence1, 2, 3, 5, 2, 1
• collecting the names of all MOF classes
• MOF!Class.allInstances()-gtcollect(e e.name)?
• checking whether all the numbers in a sequence
  are greater than 2 Sequence12, 13,
  12-gtforAll(i i gt 2)?
• o evalutes to true
• computing the sum of the positive integer of a
  sequence using the iterate instruction Evaluates
  to 12

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Enumeration and Tuples data types

• Enumeration
• Is a oclType
• Defined in target or source model
• Access enumeration value
• Tuples
• Not named
• Full declaration required
• Composite values
• Each part an OCLType
• Order not significant
• Sintaxe
• Tuplevar_name1 var_type1? init_exp1, ...,
  var_namen var_typen? init_expn
• Example
• Tupletitle 'ATL Manual', a anAuthor, editor
  'ATL Eds.'

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Map data type

• Not belong OCL
• Not named
• Full declaration required
• Example
• Map(Integer, MMAuthor!Author)?
• Map(0, anAuthor1), (1, anAuthor2)
• Common method
• get(key oclAny)?
• including(key oclAny, val oclAny)?
• union(m Map)?
• GetKeys()?
• getValues()?

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Model element data type

• Defined within source and target metamodels
• Metamodels usually define a number of different
  model elements( Class)
• Notation metamodel!class
• Handle several metamodel at once.
• Generated by rules
• Example
• Getting the names of all primitive MOF types the
  simple way
• MOF!PrimitiveType.allInstances()-gtcollect(e
  e.name)?

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ATL Comments

• 2 hyphens "--" and end at the end of the line.
• Example
• -- this is an example of a comment

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OCL Declarative Expressions

• Structure OCL code
• Advanced declarative expressions
• If-then-else-endif
• Else clause can not omitted
• Syntax

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OCL Declarative Expressions

• Let
• definition variables
• Syntax
• let var_name var_type var_init_exp in exp
• Useful debugging stage
• Uses examples
• let firstElt Real aSequence-gtfirst() in
  firstElt.square()

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Expressions tips tricks

• Evaluation mode OCL expression boolean
• Opposed common programming language

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ATL Helpers

• Methods
• Defined in Context
• Context may omitted
• Body OCL expression
• Example
• Attributes
• Constants
• accepts no parameter

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ATL Helpers
Sintaxe
Example
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Limitations of Helpers and Attributes

• Signature
• Helper name
• Helper context
• Not may define helpers in context collection type
• Library unit
• Not may helpers attributes

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ATL Rules

• Model elements achieved transformation rules
• kinds of transformation rules
• Mached rules
• Match some of the model elements of a source
  model, and to generate from them a number of
  distinct target model elements
• Called rules
• Invoked from an ATL imperative block in order to
  be executed.

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ATL imperative code

• Imperative code matched or called rules
• Statements
• assignment statements
• If
• For
• Not be used in ATL declarative code.

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Statements if and for

• ifSyntax
• ifExample

• forSyntax
• forExample

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Matched Rules

• Convenient transformation
• Enables to specify
• Which source model element must be matched
• He number and the type of the generated target
  model elements
• The way these target model elements must be
  initialized from the matched source elements

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Matched Rule Syntax
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Matched Rule

• Source pattern (FROM)?
• Specifies the type of the source model elements
  that will be matched
• Condition enable to target a subset of the
  transformation source model elements that conform
  to the source type
• Local variables section (USING)?
• Variables useds in to and do sections
• Simple target pattern element (TO)?
• Contains target pattern elements
• Specified as a set of bindings

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Matched Rule

• Iterative target pattern element
• Generate a set of target model elements
  conforming to a same type
• Keyword distinct
• Produces a target model element for each element
  belonging to a given reference ordered
  collection
• Foreach
• Imperative block section (DO)?
• Sequence imperative statements
• Initialize model elements features

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Called Rules

• Explicitly generate target model elements from
  imperative code
• Entrypoint
• has no from section

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ATL Query

• Query unit accepts sources modules and produces a
  single return value
• Syntax query query_name exp
• OCL expression
• ATL IDE StringValue.writeTo()