A Synthesis-based Approach to Transformations in an MDA Software Development Process

1

• A Synthesis-based Approach to Transformations in
  an MDA Software Development Process
• Ivan Kurtev, Klaas van den Berg
• University of Twente

2
Outline

• Alternative Transformations in MDA
• Synthesis-based Software Development Applied to
  MDA Transformations
• Example Transforming UML class models to XML
  schemas
• Alternative Space Analysis Activity
• Construction of Transformation Space
• Reduction of Transformation Space

3
Basic MDA Concepts

• Models
• CIM, PIM, PSM
• Transformations
• The MDA Pattern (from MDA Guide)

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Alternatives in MDA Transformations
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Example UML to XML Schema Transformation
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The Problem with AlternativesGeneration and
Selection

• Problem 1 Lack of support for identification of
  alternative transformations
• Transformation to the desired model may not
  always be obvious and trivial
• Problem 2 Selection among Alternatives
• Alternatives differ in their Quality properties
  such as Extensibility, Adaptability, Performance
• Alternative Transformations Analysis must be
  addressed explicitly in the MDA software
  development process!

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Alternatives Analysis in Current Software
Development Processes RUP
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RUP Analysis and Design Workflow
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RUP Activities, Steps and Artifacts
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Synthesis-based SoftwareDevelopment Process

• Unified Process does not address the alternatives
  analysis problem
• Synthesis-based Software Development Process
• Activities in Synthesis-based Process
• Technical Problem Analysis
• Solution Domain Analysis
• Alternative Space Analysis
• We focus on the third activity Alternative Space
  Analysis

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MDA Transformational Problem
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Example
UML Source Model
We aim at deriving an Extensible XML schema. New
specializations of ExamItem are expected.
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Two of many Alternative XML Schemas
ltelement nameexamItemgt ltcomplexTypegt
ltchoicegt ltelement nameopen
type/gt ltelement namemutipleChoice
type/gt lt/choicegt lt/complexTypegt lt/elem
entgt
ltelement nameexamItem
typeexamItemType
abstracttrue/gt .. lt/complexTypegt ltco
mplexType namemultipleChoiceTypegt
ltcomplexContentgt ltextension
baseexamItemTypegt .
lt/extensiongt lt/complexContentgt lt/complexTypegt lt
element namemultipleChoice
typemultipleChoiceType
substitutionGroupexamItem/gt
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Alternative Space Analysis as part ofthe
Synthesis Process
Alternative Space Analysis Activity
Workflow of the Alternative Space Analysis
Activity
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Step 1 Constructing Transformation Space

• Set of dimensions one dimension for every
  (relevant) element from the source model
• A coordinate set for every dimension

CT Complex Type E Element MG Model Group AG
Attribute Group Der Derivation Subst
Substitution Cont Containment Ref
Reference (Derived from XML Schema Meta-model)
4 x 4 x 580 alternatives
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Step 2 Reducing Transformation Space
after selection
after exclusion
(ExamItem.E or ExamItem.CT) and (Open.E or
Open.CT)
ExamItem_Open.E or ExamItem_Open.Ref
12 alternatives
20 alternatives
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Step 3 Reducing Transformation Space based
onQuality Requirements

• In this example the Quality Model is the model of
  Extensibility
• Model elements are
• Extensible (Exts)
• Inextensible (InExts)
• Our technique allows merging of quality
  properties with a transformation space

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Set of Alternative Transformations

• After applying some reduction steps and taking
  into account the quality properties, two
  alternative transformations from the space are
  selected

Dimension
N ExamItem Open ExamItem_Open
1 E E E Subst
2 E E CT Der
Alternative Transformation
Coordinate
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Conclusions

• We presented an Activity of Alternative Space
  Analysis as a part of Synthesis-based Software
  Development Process for MDA transformations
• Transformation Space
• Is NOT a transformer
• Is NOT a transformation specification
• Not all alternatives in the Transformation Space
  are explicitly generated

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Future Work

• Study the full synthesis-based process
• Experiments with more complex mappings (not only
  11 as in the example)
• Experiments with more complex quality models
• Tool support