An Overview of Model-Driven Engineering and Architecture

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An Overview of Model-Driven Engineeringand
Architecture

• Jacques Robin

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Outline

• What is MDA?
• MDA Principles
• MDA Process and Software Reuse
• OMG MDA standards
• Third party providers roles, standards and tools

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What is Model-Driven Architecture (MDA)?

• An initiative from the Object Management Group
  (OMG) started in 1997, www.omg.org/mda/
• New paradigm of software development
• Goals
• Maximize software reuse across platforms
• Solve the second order interoperability problem
  among different middleware (which goal was to
  solve the first order interoperability problem
  among programming languages)
• Raise the level of abstraction where most
  development effort is spent from code to model
• Provide standards to automate the entire software
  development process through a model
  transformation approach
• Reuses and extends previous standards
• Unified Modeling Language (UML), by OMG
• Meta-Object Facility (MOF), by OMG
• eXtensible Markup Language (XML), by W3C
  (World-Wide Web Consortium, www.w3c.org/xml/)

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MDA Principles

• The most valuable, durable, reusable assets
  produced during the development process is not
  code but models
• Far more significant and cost-effective quality
  gains are achievable by improving design and
  models than by improving code
• Benefits from careful, detailed, explicit
  modeling is not limited to the application under
  development but extend to all the processes,
  artifacts, languages, tools and platforms used
  for this development

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MDA Principles

• A high degree of software process automation can
  be achieved by
• Building a variety of models, each one with a
  different role in the process,
• Making each of these models machine processable
  by expressing it in a semi-formal notation devoid
  of natural language
• Defining this notation itself as an
  object-oriented model (called a meta-model)
• Storing all models and meta-models with
  traceability links in a repository accessible to
  model manipulation software
• Abstracting generic transformations between
  pairs of meta-models that computationally codify
  the know how for one software process stage
• Using model transformation engines to apply
  these transformations to the source model of a
  process stage and generate the target model of
  that stage
• Define meta-models for the meta-modeling and
  model transformation notations

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CurrentMainstreamOOSE
Abstraction
Executability
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Manual MDEExtreme Modeling
Abstraction
Executability
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Transformation Based MDEUML Programming
Abstraction
Fully Refined Requirement Analysis w/ UML/OCL
or DSPIML CASE Tool
High-Level Realization PIM Transformation Base
High-Level Realization PIM Transformation Developm
ent
Fully Refined Specification Platform Independent
Model (PIM) UML/OCL or DSPIML
High-Level Design w/ UML/OCL or DSPIML CASE Tool
PIM to PSM Translation Transformation Development
Realization PIM Refinement Transformation Developm
ent
PSM to Source Code Translation Transformation Base
High-Level Realization PIM UML/OCL or DSPIML
PIM to PSM Translation Transformation Base
Realization PIM Refinement Transformation Base
DesignFull Refinement w/ UML/OCL or DSPIML CASE
Tool
Fully Refined Realization PIM UML/OCL or
DSPIML
PSM Profiled UML/OCL or DSPSML
Source Code to Executable Code Translation
PSM to Source Code Translation
Source Code
Executable Code
Executability
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MDA Software Process
Domain Computation Independent Model
Application Requirement Model
Platform Model
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Artifact Reuse with MDA Process
Application A Requirement Model
Platform P Model
Application A Platform P Specific Model
Testing Model AP
Application A Platform Independent Model
Application B Platform Independent Model
Domain Computation Independent Model
Application B Requirement Model
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Automated MDA Process Design
Design Transformations
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Automated MDA Process Implementation
PIM ? PSM Transformations
Platform Model
Application Platform Specific Model
Application Platform Independent Model
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Automated MDA Process Code Generation
Source Code Meta-Model
Code Generation Transformations
Application Platform Specific Model
Application Source Code
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Automated MDA Process Test Generation
Test Generation Transformations
Application Platform Specific Model
Testing Model
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Automated MDA Process Reverse Engineering
PSM ? PIM Reverse Engineering Transformations
Platform Model
Application Platform Specific Model
Application Platform Independent Model
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Automated MDA Process PIM Refactoring
PIM Refactoring Transformations
Refactored PIM
Legacy PIM
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Automated MDA Process PSM Refactoring
PSM Refactoring Transformations
Refactored PSM
Legacy PSM
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Automated MDA Process Code Refactoring
Source Code Meta-Model
Source Code Meta-Model
Code Refactoring Transformations
Refactored Source Code
Legacy Source Code
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OMG Tasks in MDA Initiative

• Define meta-modeling standard Meta-Object
  Facility (MOF)
• Define general-purpose visual modeling standard
  Unified Modeling Language (UML)
• Define complementary general-purpose, semi-formal
  textual modeling standard to make both MOF
  metamodels and UML models more precise and devoid
  of natural language Object Constraint Language
  (OCL)
• Define general-purpose, both machine-processable
  and user-readable persistent textual format for
  both MOF meta-models and UML models XML Model
  Interchange (XMI)
• Define model manipulation standard Query View
  Transform (QVT)
• Each of these standards to be defined in terms
  of
• Abstract syntax as a MOF meta-model
• Concrete syntax (visual or textual)
• Formal semantics (very partial up to now)

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Relationships between OMGs MDA standards
UML2
UML2 Infrastructure
...
Constructs
Associations ...
merge
merge
merge
merge
merge
merge
MOF2

merge
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Example Meta-Model

extends
extends
MOF Meta-Model of Use-Cases
1 ..
1 ..
0 ..1
includes
e-Store
OrderItem
UML Model Use-Case Diagram
ValidateCart
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Example Meta-Meta-Model
MOF Meta-Model of MOF Meta-Model
1 ..
extends
MOF Meta-Model of UML Use-Cases
extends
1 ..
1 ..
0 ..1
includes
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Example of XMI Encoding

• ltumlModelgt
• ltuseCase id oiucgt
• lttitle,visib pubgt orderItem lt/titlegt
  lt/useCasegt ltuseCase id vcucgt
  lttitle,visib pubgt validateCart lt/titlegt
  lt/useCasegt
• ltactor id cagt ltname, visib pubgt
  Client lt/namegt lt/actorgt
• ltsystem id essgt ltname, visib pubgt
  e-Store lt/namegt lt/systemgt
• ltactor2useCase id ca2oiucgt
• ltin idref ca/gt ltout idref oiuc/gt
  lt/actor2useCasegt
• ltactor2useCase id ca2vcucgt
• ltin idref ca/gt ltout idref vcuc/gt
  lt/actor2useCasegt
• lt/umlModelgt

e-Store
orderItem
validateCart
Client
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Other Stakeholders Tasks in MDA Initiative

• Platform providers
• Define platform model as UML Profile or PSM
  meta-model in MOF
• Multiple domains or wide domain application
  providers
• Use only standards defined by OMG and platform
  providers
• Narrow domain application providers
• Define special-purpose modeling languages in MOF
• MDA CASE tool providers
• Implement model base development and management
  services such as edition, syntactic validation,
  import, export, persistence, query, access
  control, versioning and traceability for
• Models in UML, OCL and MOF-specified
  user-defined languages
• MOF meta-models
• QVT and MOF-specified model transformation
  languages
• Define APIs to program new model processing
  services on top of theses basic services
• Implement model transformation engines based on
  MOF and QVT
• Implement code and test generation services from
  PSM

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MDA Third-Party Standards and Tools

• Java Modeling Interface (JMI)
• Standard from Java Community Process (JCP)
• Defines a set of Java interfaces to process
  models represented as Java objects
• Reflective interfaces define general model
  manipulation operations that are independent of
  the models meta-model
• Taylored interfaces define model manipulation
  operations that are specific to models that
  follow a given meta-model
• Taylored interfaces can be automatically
  generated from a MOF meta-model
• Eclipse Modeling Framework (EMF)
• Standard from the Open Source Java-Based IDE
  project Eclipse (www.eclipse.org)
• Plug-in for Eclipse IDE framework
• Implements similar reflective and taylored
  interfaces than JMI
• Implements generation of taylored interface from
  MOF meta-model
• Implements generation of Eclipse-integrated
  model editor from MOF meta-model

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Model representation as XML document and Java
Objects
File System
Main Memory
Model
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Java Model Representation vs. Implementation

• Java objects generated using the taylored and
  reflective interfaces of JMI or EMF merely
  represent model elements
• They only provide a handle to process these
  elements using Java
• They are completely different from Java objects
  that implement these model elements
• Though among many other uses, theses model
  representation Java objects can be used as input
  to program in Java the generation of model
  implementing Java objects
• But they could also be used to generate a C or
  Prolog implementation of the application or any
  other MDA service
• Java model representation objects are useful for
  MDA CASE tools during the development process of
  an application, whereas Java model implementation
  objects are useful for this application
• In one case, Java is used to implement CASE tools
  functionalities, in the second case, Java is used
  to implement application functionalities