RMLL - Eclipse Acceleo Day - MDSD Scaffolding and Acceleo - Cédric Vidal - 1.1

MDSD
Scaffolding
and
Cédric Vidal, ProxiAD
Friday 10th July 2009
Version 1.0

Who are we ?
ProxiADGroup
SSII specialized in objectorienteddevelopment
Dedicatedingenieringprocess industrialisation team
Using MDA since 2004 on J2EE projects
Cédric Vidal
J2EE & MDA Architect
ProxiAD IDF Technical Leader

Agenda
WhatisScaffolding ?
Scaffolding in software
Scaffoldingapplied to MDSD
MDSD Scaffoldingapproaches
Acceleo MTL
Demo
Benefits
Links

Whatisscaffolding ?
Scaffolds are temporary structures that physically support workers while they complete jobs that would otherwise be impossible(HH93, p138)

Scaffolding in software
Ruby on Rails
*Rails scriptingframeworksbringblazingfastproductivity in theirownspecifictechnologicalspace
MainlythroughScaffolding !

Ruby on Rails Scaffolding
Meta-Programming
Scaffoldingworksat the code level
Scaffoldingengineoperates on code as a model
Can beeither
Static : on demand
Dynamic : transparently on yourbehalf
Entity.rb
DAO.rb

Others
Ruby On Rails
Grails
Spring ROO
Play!
CakePHP
Monorail
Symfony
…

What’s the point ?
Model-Drivenbringsquality, durability, maintainability
What about productivity ?
Code generationtemplateswritingalready productive withAcceleo (old and MTL)
Goal: Enhancemodelingproductivity

Objective
Achievebothquality AND productivity
BringScaffolding to Modeling

WhatisScaffoldingapplied to Modeling ?
Creating partial model structures on behalf of the designer that hewouldotherwise have to create by himself

Model Scaffoldingtaxonomy
Blind versus In-PlaceScaffolding
Static versus DynamicScaffolding
The greener the better

Model Scaffoldingtaxonomy
Classical code generation
Compensated code generation
« Blind » scaffolding
« In-Place » scaffolding
Eachstatic or dynamic

Sampleproblemdomain
3-Tiers Architecture
DSL containing concepts
Entity
DAO
Service
Java code isgenerated
Légende
Entity or DAO
File
Service
Generation
Reference
Model separation
Color code
Hand-written
Scaffolded
Generated

Classical code generation 1/2
Entities are modeled
Entity and DAO source codes are generatedfrom the modeledEntity
Problem: What if youwant to definequeries in your model ?
Model
Entity
Text
DAO.java
Entity.java

Classical code generation 2/2
Entity and DAOs are modeled
Entity source code isgeneratedfrom the modeledEntity
DAO source code isgeneratedfrommodeled DAO
DAOswhich are not modeled are not generated
Problem: You need to define all DAOs…
Eventhosethatonly do CRUD
Model
DAO
Entity
Text
DAO.java
Entity.java

Compensated code generation
Source code isstillgeneratedfor modeledelements
For Entitieswhich have no modeled DAO, wecompensate by generatingsource code for the DAO from the modeledEntity
Advantage: Only custom DAOs are modeled
Problem: DAO code generationlogicisduplicated
Entity -> DAO.java
DAO -> DAO.java
Model
Entity
One
DAO
One
Entity
Two
One.java
TwoDAO.java
Two.java
OneDAO.java
Text

Generation « Blind » Model Scaffolding
Model i
Entity
Two
Each model is a step in the MDSD chain
An intermediatestepisintroduced
Each model canonly « see » the model before
Existingelements are copied as is
A DAO isgenerated for eachentitywhich has no DAO
Advantage: Only one DAO code generationlogic
Problem: How do youreferencescaffoldedelements
DAO
TwoDao
Entity
One
Model i-bis
Entity
Two
DAO
TwoDao
Entity
One
DAO
OneDao
Model i+1
One.java
TwoDAO.java
Two.java
OneDAO.java

How to referencescaffoldedelements ?
The problemisillustrated by introducing a service
The ‘Alpha’ service canreference the modeled DAO ‘TwoDao’ but not the scaffolded DAO ‘OneDao’
The scaffolded DAO ‘OneDao’ islocated in a model that the ‘Alpha’ service cannotsee
Problem: « Blind » scaffoldingdoesn’tallowscaffoldedelementsreferencing
Modèle i
DAO
TwoDao
Entity
Two
Entity
One
Service
Alpha
Modèle i-bis
DAO
OneDao
Entity
One

« In-place » Model Scaffolding
‘OneDao’ DAO isscaffolded in the same model as Entity ‘One’
The DAO is « visible » withoutbeingmaterialized in the input model
Advantage: Le ‘Alpha’ service canreference the scaffolded DAO ‘OneDao’
Problem: How to customize a scaffoldedelement ?
Model i
Entity
One
DAO
OneDao
Service
Alpha
Model i+1
One.java
AlphaService.java
OneDao.java

Takeover 1/3: Overview
User cantake over scaffoldedelements
The over takenelementisthenmaterialized in the input model
Advantage: The DAO canbecustomized
Iteration n
Entity
One
DAO
OneDao
Service
Alpha
Iteration n+1
Entity
One
DAO
OneDao
Service
Alpha

Takeover 2/3: Zoom
After the DAO taking over, CRUD methods are stillscaffolded
Advantage: No need to manually input previouslyscaffoldedelements
DAO
OneDao
Iteration n
Entity
One
Service
Alpha
create
read
update
delete
Iteration n+1
DAO
OneDao
Entity
One
Service
Alpha
create
read
update
delete

Takeover 3/3: Customisation
Iteration n+1
Let’sadd a finderfinder
CRUD methods are stillscaffolded
Advantage: Onlycustomizations are hand written, CRUD methods are scaffolded
DAO
OneDao
Entity
One
Service
Alpha
create
read
update
delete
Iteration n+2
DAO
OneDao
Entity
One
Service
Alpha
create
read
update
delete
myFinder

Deletion 1/2: The problem
Whathappens if the user deletes an element for whichelementswerescaffolded ?
Scaffoldedelements must alsobedeleted
Model i
Entity
One
DAO
OneDao
Service
Alpha
Model i+1
One.java
AlphaService.java
OneDao.java

Deletion 2/2: solutions
Need to keeptrackof scaffoldedelements
Onlyreally a problemwithdynamic « in-place » scaffolding
For static and/or « blind » scaffolding, scaffoldedelementscanjustbecomputed all over again

Model scaffoldingcomparison

WhatScaffoldingengine ?
A model to model transformation engine ?
ATL
Xtend
QVT Operational
QVT Relational
Obeo Transfo
…
A ruleengine ?
Drools
Any OO RuleEngine …

A ruleengine ??
Scaffoldingrules as production rules
The model as a workingmemory
Model elements as facts
When a givenconditionis met, new factsare insertedintoworkingmemory
Those new facts are attached to the model as new elements

Ruleenginesyncprocess
Working Memory
Model
Entity
One
synchronize
Entity
One
reference
ScaffoldingRule
reference
DAO
OneDao
DAO
OneDao
synchronize

Droolssamplerule
SampleDrools DAO scaffoldingrule

Pros and cons
M2M Engine
Pros
Leveragesexistingskills
Sametechnologicalspace
Suited for staticscaffolding
Cons
Hard to use for dynamic « in-place » scaffolding
RuleEngine
Pros
Nativelysuited for dynamic « in-place » scaffolding
Can do staticscaffolding as well
Cons
Differenttechnologicalspace as the rest of the MDSD technologies
Cannotleverageexistingskills and transformations

Scaffoldingdemo
Dynamic « In-Place » DSL Scaffoldingdemo
Uses
A DSL withEntity, DAO and Service concepts
An EMF.Edit editor
DroolsRuleEngine as the scaffoldingengine

MDSD Scaffoldingbenefits
Acceleratesmodeling
Allows to quickly come up with a working model
The user startsfrom the beginingwith a complete model (complete in the direction the scaffoldingtakeshim)
Provides the user with a fastfeedback
Allows to enrich the input model as well as facilitatingits usage for the new user
Bringsflexibilitywhilekeepingsimplicity
Scaffoldingcanbecomplemented by code generationand model validation
The user canwheneverhewantstake over the scaffoldedelements in order to customizethem

Otherintegrations
Structured model editors
EMF.Edit
GraphicalDSLs
GMF
Obeo Designer
TextualDSLs
Xtext
UML models
Papyrus/UML2Tools/Topcased
IBM RSM

Links
JBossDroolshttp://jboss.org/drools/
Eclipse Acceleo MTLhttp://bit.ly/yS3gp
ProxiAD’s Bloghttp://blog.proxiad.com
Cédric Vidal’s Bloghttp://blog.proxiad.com/author/cvidal/
Cédric Vidal’sTwitterhttp://twitter.com/cedricvidal

References
HH93 - Herber, H., & Herber, J. (1993). Teaching in Content Areas With Reading, Writing, and Reasoning. Allyn & Bacon: Needham Heights, M.A.

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RMLL - Eclipse Acceleo Day - MDSD Scaffolding and Acceleo - Cédric Vidal - 1.1

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RMLL - Eclipse Acceleo Day - MDSD Scaffolding and Acceleo - Cédric Vidal - 1.1 — Presentation Transcript