The document discusses model-to-text (M2T) transformations and code generation. It describes how M2T transformations can be implemented using general purpose programming languages or specialized M2T transformation languages. Template-based M2T transformation languages like Acceleo separate static and dynamic code, provide an explicit output structure, and support declarative querying of models. Acceleo templates define tags for files, control structures, queries, expressions, and protected regions to generate target code from models.

1. Model-To-Text Transformation Language chapter 9 – J Cabot
Model-to-Text
Transformations
Mr M.LotfiNia
Email:majidlotfinia12@yahoo.com
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2. Model-To-Text Transformation Language chapter 9 – J Cabot
Contents
• Basicsof Model-Driven CodeGeneration
• CodeGeneration Through Programming Languages
• CodeGeneration Through M2T Transformation Languages
 Template-Based Transformation Languages
 Benefitsof M2T Transformation Languages
 Tools
 Acceleo
• Mastering CodeGeneration
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3. Model-To-Text Transformation Language chapter 9 – J Cabot
Basic Defination
• Codegeneration hasalong tradition in softwareengineering
• Main goal of MDE: runing system out of themodel
• code-generation in compiler istheprocessof transforming
sourcecodeinto machinecode
• M2T transformation in theareaof MDE
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4. Model-To-Text Transformation Language chapter 9 – J Cabot
MDE code-generation
• code-generation istheprocessof transforming modelsinto
sourcecode
• MDE code-generation isbuilt on top of existing compilersfor
programming languages
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5. Model-To-Text Transformation Language chapter 9 – J Cabot
Questions
How much is generated?
How to generate?
What is generated?
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6. Model-To-Text Transformation Language chapter 9 – J Cabot
How much isgenerated?
• which partsof thecodecan beautomatically generated from
models
• onelayer of theapplication iscompletely generated while
another layer may becompletely manually
developed.
• onelayer isonly partially generated and some
missing partshaveto bemanually completed
full or only a partial ?full or only a partial ?
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7. Model-To-Text Transformation Language chapter 9 – J Cabot
Partial code-generation
• using only codegeneration for certain partsof amodel
• other partsarenot touched by thecodegenerator and haveto
beimplemented manually.
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8. Model-To-Text Transformation Language chapter 9 – J Cabot
What isgenerated?
• kind of sourcecodeto generate?
• conciseaspossible
• Turing test for codegenerators
• avoiding to reinvent thewheel
• thelesscodeto generatewhich isableto represent asystem,
thebetter.
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9. Model-To-Text Transformation Language chapter 9 – J Cabot
How to generate?
• When therequirementsfor thecode-generation arespecified,
namely what hasto beachieved by thecodegenerator
• which partsaregenerated?
• which target languagesareused?
• Ho w to implement theserequirements?
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10. Model-To-Text Transformation Language chapter 9 – J Cabot
Code-generation
• Code-generation may bedescribed asthevertical transition
from modelson ahigher-level of abstraction to lower-level
artifacts
• codegeneratorshaveto bridgethisgap in theabstraction
which may beachieved in different
ways.
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11. Model-To-Text Transformation Language chapter 9 – J Cabot
implementation of acodegenerator
• Theimplementation of acodegenerator can be
based two approach:
1. MDE principlesapproach
2. Traditional programming approach
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12. Model-To-Text Transformation Language chapter 9 – J Cabot
Codegeneration through programming
languages
• A codegenerator may beimplemented asaprogram
• Using themodel API to
 Processtheinput models
 Generateout code
 Print out codestatementsto afile
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13. Model-To-Text Transformation Language chapter 9 – J Cabot
Model API
• Model API automatically generated from themetamodel
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14. Model-To-Text Transformation Language chapter 9 – J Cabot
Model API
• For each featureof themetaclasses, corresponding getter and
setter methodsaregenerated on theJavaside
• Thismeans, amodel can beread, modified, and completely
created from scratch by using Javacodeinstead of using
modeling editors.
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15. Model-To-Text Transformation Language chapter 9 – J Cabot
GPL-based codegenerators
• wepresent how aGPL may beemployed to develop acode
generator
• By thiswedemonstrate:
1) how modelsareprocessed using amodel API generated from
themetamodel
2) highlight thefeaturesneeded to realizeacodegenerator
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16. Model-To-Text Transformation Language chapter 9 – J Cabot
Phasesfor codegenerator
1. Load model
 Modelshaveto bedeserialized from their XMI representation
to aobject graph loaded in-memory.
1. Producecode
 Collect themodel information needed for generating thecode
by using themodel API to processthemodels
1. Writecode
 Saved codeto theoutput file
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17. Model-To-Text Transformation Language chapter 9 – J Cabot
Phasesfor codegenerator
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18. Model-To-Text Transformation Language chapter 9 – J Cabot
Java-based CodeGeneration - Load Model

19. Model-To-Text Transformation Language chapter 9 – J Cabot
Java-based CodeGeneration - ProduceCode

20. Model-To-Text Transformation Language chapter 9 – J Cabot
Codegenerator example
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21. Model-To-Text Transformation Language chapter 9 – J Cabot
Advantage
• no additional programming skillsareneeded
• It issufficient to know :
 programming languagesused for developing thegenerator and
used astarget
 work with themodel API.
• no additional toolsareneeded for thedesign timenor for the
runtime
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22. Model-To-Text Transformation Language chapter 9 – J Cabot
disadvantage
• Intermingled static/dynamic code
 Thereisno separation of static co de and dynamic co de
Static co de: codethat isgenerated in exactly thesameway for
every model element
packagedefinition
Imports
Dynamic code: which isderived from model information
• Missing reusablebasefunctionality
 Codehasto bedeveloped for reading input modelsand
persisting output codeagain and again for each codegenerator
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23. Model-To-Text Transformation Language chapter 9 – J Cabot
disadvantage
• Nonegraspableoutput structure
 Thestructureof theoutput isnot easily graspablein thecode
generator specification
 Theproblem isthat theproduced codeisembedded into the
producing code
• Missing declarativequery language
 No declarativequery languagefor accessing model
information isavailable
 thusmany iterators, loops, and conditionsaswell astypecasts
unnecessarily lead to ahugeamount of code.
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24. Model-To-Text Transformation Language chapter 9 – J Cabot
Eliminatedisadvantages
• DSLshavebeen developed for generating text from
models.
• Thishasalso lead to an OMG standard called MOFMo delto
Text Transfo rmatio n Language (MOFM2T)
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25. Model-To-Text Transformation Language chapter 9 – J Cabot
Codegeneration through M2T TL
• M2T transformation languagesaim at improving the
codegenerator development by tackling theaforestated
drawbacksof GPL-based codegenerators
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26. Model-To-Text Transformation Language chapter 9 – J Cabot
TemplateBaseM2T TL
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27. Model-To-Text Transformation Language chapter 9 – J Cabot
TemplateBaseM2T TL
• meta-market:
 simpletext fragmentsfor thestatic part
 placeholdersand haveto beinterpreted by atemplate engine
which processesthetemplatesand queriesadditional data
sourcesto producethedynamic parts.
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28. Model-To-Text Transformation Language chapter 9 – J Cabot
Benefit M2T Transformation Language
• Separated static/dynamic code
 static text elementsshared by all artifactsaswell asdynamic
partswhich haveto befilled with information specific to each
particular case
• Explicitoutputstructure
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29. Model-To-Text Transformation Language chapter 9 – J Cabot
Benefit M2T Transformation Language
• Declarativequery language
 codeisused to accesstheinformation stored in themodels
 current M2T transformation languagesalso allow to useOCL
• Reusablebasefunctionality
 allow to directly read in modelsand to serializetext into files
by just defining configuration files
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30. Model-To-Text Transformation Language chapter 9 – J Cabot
Overview of telmplate-baseTL
• Different template-based languagesexist which may be
employed to generatetext from models.
• XSLT:
 XMI serializationsof themodelsmay beprocessed with XSLT
 directly operating on themodel level
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31. Model-To-Text Transformation Language chapter 9 – J Cabot
Overview of telmplate-baseTL
• JET:
 JavaEmitter Template
 first approachesfor developing code-generation for EMF-based
models
 JET isnot limited to EMF-based models
 In JET every Java-based object istransformableto text
 JET templatesaretransformed to pureJavacodefor execution
purposes
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32. Model-To-Text Transformation Language chapter 9 – J Cabot
Overview of telmplate-baseTL
• Xpand:
 ThisM2T transformation languageemerged in the
openArchitectureWareproject
 migrated to Eclipse
 hosted asan Eclipsemodeling project
 languagefor querying modelswhich isamixtureof Javaand
OCL
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33. Model-To-Text Transformation Language chapter 9 – J Cabot
Overview of telmplate-baseTL
• MOFScript:
 providing similar featuressuch asXpand
 OMG standardization effort providing astandardized language
for M2T transformations
 availableasan Eclipseplug-in and supportsEMF-based
models
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34. Model-To-Text Transformation Language chapter 9 – J Cabot
Overview of telmplate-baseTL
• Acceleo
 provideapragmatic version of theM2T transformation
standard of theOMG for EMF-based models
 providesfull OCL support for querying models
 maturetool support which hasproven useful in industry
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35. Model-To-Text Transformation Language chapter 9 – J Cabot
Acceleo
• Acceleo isaprotagonist to demonstrateM2T transformation
languages
• practical relevanceand maturetool support
• offersatemplate-based languagefor defining code-generation
templates.
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36. Model-To-Text Transformation Language chapter 9 – J Cabot
Acceleo
• comeswith apowerful API supporting OCL
• advanced functionsfor manipulating strings
• powerful tooling such as:
 editor with syntax highlighting
 error detection
 codecompletion
 refactoring, debugger, profiler
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37. Model-To-Text Transformation Language chapter 9 – J Cabot
Acceleo tag
• Acceleo templatelanguageoffersseveral meta-markerswhich
arecalled tags
• Files
 fileshaveto beopened, filled, and closed
 Thepath and thefilenameareboth defined by an attributeof
thetag
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38. Model-To-Text Transformation Language chapter 9 – J Cabot
Acceleo tag
• Control structures:
 tagsfor defining control structuressuch as:
loops(for tag)
conditional branches(if tag)
• Queries
 OCL queriescan bedefined (query tag)
 used to factor out recurring code
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39. Model-To-Text Transformation Language chapter 9 – J Cabot
Acceleo tag
• Expressions
 generated text to producethedynamic partsof theoutput text
 call other templatesto includethecodegenerated
 Calling other templatescan becompared to method
callsin Java
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40. Model-To-Text Transformation Language chapter 9 – J Cabot
Acceleo tag
• Protected areas
 support projectswhereonly partial code-generation
 partial code-generation supported by protected tag
 Protected areasareused to mark sectionsin thegenerated code
that shall not beoverridden again by subsequent generator
runs.
 Thesesectionstypically contain manually written code
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41. Model-To-Text Transformation Language chapter 9 – J Cabot
Acceleo codegeneration example
• Listing 9.2 in thebook, page135
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