Guest Talk Vienna

Aspect-Oriented Modeling:
Oxymoron or Pleonasm?
Jean Bézivin
Université de Nantes
Faculté des Sciences et Techniques
2, rue de la Houssinière BP 92208
44322 Nantes cedex 3, France
Jean.Bezivin@sciences.univ-nantes.fr
Guest talk given at AOPDCD'2002, Vienna, July 2nd 2002

AOPDCD'2002, Vienna, July 2nd 2002
Conditions for a Possible Synergy?
AOSD MDA
[Aspect-Oriented Modeling?]

Main point of the presentation
Objects everywhere
 How will model engineering help capturing aspect management in
software development?
 How this could fit in the OMG MDA initiative?
 Which kind of aspects could be captured by separate models?
 Which kind of operations (separation, weaving, etc.) could be
defined on models
 How may these different concerns, represented by coordinated
non executable abstract models, be operationalized (i.e. mapped
on equivalent executable models)
Models

Agenda
A point of vocabulary
Paradigm evolution : from objects &
components to models
What is the MDA?
Models as an explicit specification of
aspects
Conclusions: AOSP vs MDA/MDE

Oxymoron
A rhetorical figure in which an epigrammatic
effect is created by the conjunction of
incongruous or contradictory terms
A rhetorical figure in which incongruous or contradictory terms are
combined, as in a deafening silence and a mournful optimist.
The American Heritage® Dictionary of the English Language, Fourth Edition
A figure in which an epithet of a contrary signification is added to a word -
e. g., cruel kindness - laborious idleness.
Webster's Revised Unabridged Dictionary, © 1996, 1998 MICRA, Inc.
n : conjoining contradictory terms (as in 'deafening silence')
WordNet ® 1.6, © 1997 Princeton University

Oxymora
active waiting - acute dullness - Advanced BASIC - almost exactly -
alone together - clearly ambiguous - clearly confused - clearly
misunderstood - conciliation court - constant variable - dangerously safe -
deafening silence - definite maybe - diet ice cream - even odds - exact
estimate - extensive briefing - extinct life - fish farm - flexible ethics -
found missing - fresh-frozen - friendly fire - genuine imitation - good shit
- hells angels - holy war - home office - idiot savant - industrial park -
intense apathy - jumbo shrimp - linear curve - liquid gas - little giants -
living dead - long sleeved t-shirt - minor crisis - new classic - non-
alcoholic wine - non-dairy creamer - non-working mother - old news - only
choice - open secret - original copies - paid volunteer - passive aggression
- peace offensive - plastic glasses - plastic silverware - pretty ugly -
randomly organized - real potential - resident alien - sad clown - scheduled
spontaneity - seriously funny - silent scream - sweet sorrow - synthetic
natural gas - temporary tax increase - tragic comedy - uncrowned king -
vaguely aware - virtual reality - working vacation - etc.

Pleonasms
 Pleonasms are the opposites (antonyms) of oxymora. A pleonasm consists of
several concepts (usually several words) that are redundant, e.g. "at this
moment in time." (presumably these five words mean "now.")
 pleonasm PLEE-uh-naz-uhm, noun:
1. The use of more words than are necessary to express an idea - as, "I saw it
with my own eyes."
2. An instance or example of pleonasm.
3. A superfluous word or expression.
 from Latin pleonasmus, Greek pleonasmós ('more-ness') excess, redundancy]. A
traditional term for the use of more words than necessary, either for effect or
more usually as a fault of style, and any instance of that use, as in: Could you
repeat that again? rather than Could you say that again? or Could you repeat
that? - They both got one each rather than They both got one or They got one
each - That's a more superior product (superior already denotes 'more') - It's a
really new innovation (an innovation is already new). Some common pleonasms
attract little comment, such as free gift (gifts are by definition free) and plans
for the future (plans cannot be about the present or past).
 The Oxford Companion to the English Language, © Tom McArthur 1992

Pleonasms
 absolutely essential - a cappella without music - advance warning -
affirmative yes - A.M. in the morning - attach together - autobiography
of my life - bad evil - classic tradition - classify into groups - climb up -
close proximity - cold ice - collaborate together - combined together -
dark night - DOS operating system - empty hole - foreign imports -
frozen ice - grateful thanks - handwritten manuscript - hot fire -
imminent at any moment - individual person - invited guests - join
together - joint collaboration - joint cooperation - knowledgeable
experts - little baby - long litany - major breakthrough - malignant
cancer - may possibly - mental thought - merge together - mutual
cooperation - near proximity - new discovery - new innovations - new
neophyte - new recruit - nostalgia for the past - old senior citizens -
oral conversation - original founder - original source - pair of twins -
past history - positive yes - postponed until later - potentially capable -
repeat again - round circle - specific examples - top priority -
unexpected surprise - wordy and verbose - youthful teenagers

Paradigm evolution
 OT (Object Technology) has
got to answer many difficult
problems since its initial
industrial discovery in the
80's.
 Generally OT did not
succeed very well in finding
good internal solutions to
these challenges.
 As a consequence, the
proposed solutions are often
ad-hoc, informal, and even
baroque. They are are
difficult to generalize and
hard to combine. They often
don't scale up.
Object
Technology
Use
cases
Aspects
Patterns
etc.

Paradigm evolution
 MT (Model Technology) seems to
be in a position to meet some of
these challenges to which OT was
not able to find an internal
solution.
 Among these we may quote:
 Aspect separation
 Homogeneous handling of functional
and non-functional attributes
 Integration of different paradigms
(rules, services, processes,
architecture, etc.)
 MT seems able to subsume OT and
to offer a realistic migration path
from present object and
component solutions to more
ambitious regular and scalable
organizations.
OT
Use
cases
Aspects
Patterns
etc.
MT
QoS
Rules
Processes
Applications
Services

MDA: The new OMG vision
OMG is in the ideal position to provide the model-based
standards that are necessary to extend integration
beyond the middleware approach…Now is the time to
put this plan into effect. Now is the time for the
Model Driven Architecture.
Richard Soley and the OMG staff,
MDA Whitepaper Draft 3.2
November 27, 2000

The next steps
CORBA was a
powerful first step,
but we have more
steps to take.
Fred Waskiewicz,
OMG Director of Standards

Angry end-users
We don't want anymore to pay such a high price
for simply moving our information system to a new
middleware platform (COM, CORBA, Java, HTML,
XML, DotNet, etc.) when our business system
stays stable.
We are prepared to pay a last price for building
the abstract models of our business and services
that will guarantee us against technological
obsolescence.
From there, any platform provider will also have to
provide the mapping solutions from standard
business models before we buy.

The sequence has no end
It's difficult - - in fact, next to impossible - -for a large enterprise to standardize
on a single middleware platform. Some enterprises found themselves with more than
one because their different departments have different requirements, others
because mergers or acquisitions created a mix. Even the lucky enterprise with a
single middleware choice still has to use other technologies to interoperate with
other enterprises and B2B markets.
The middleware environments that are most visible today are CORBA, Enterprise
JavaBeans, messageoriented middleware, XML/SOAP, COM+ and .NET. However,
over the past decade or so, the middleware landscape has continually shifted. For
years we've assumed that a clear winner will emerge and stabilize this state of flux,
but it's time to admit what we've all suspected: The sequence has no end! And, in
spite of the advantages (sometimes real, sometimes imagined) of the latest
middleware platform, migration is expensive and disruptive. (We know an industry
standards group that, having migrated their standard infrastructure twice already,
is now moving from their latest platform du jour to XML.)
from Richard Soley and the OMG staff,
MDA Whitepaper Draft 3.2, November 27, 2000

The middleware war is over
COM+
DCOM
CORBA
IIOP
Microsoft
C# &
DotNet
XML
SOAP
Sun's
Java
EJB
HTTP
HTM
L
 There is no clear
winner nor loser
 The next battlefield
will be model
transformation
 The OMG's Model
Driven Architecture
(MDA) initiative is
aimed at using
modeling and meta-
modeling to drive the
design and
implementation of
distributed systems.
+ the next wonderful
Middleware platform (~2005)
Sun's reaction
to
C# & DotNet ?

Mapping to multiple and
evolutive platforms
COM+
DCOM
CORBA C#
DotNet
XML
SOAP
Java
EJB HTTP
HTM
L
 MOF along with UML is
a core technology for
MDA.
 Technology neutral
models of systems can
be mapped to
implementations that
use a variety of
middleware
technologies (easy to
say, more difficult to
implement)
UML and MOF compliant
platform independent models

Various platforms
CORBA
Java/EJB C#/DotNet Web/XML/SOAP
PIM
etc.
Platform-Independent
ModelMulti-target
code generation
+ SVG, GML, Delphi, etc.

Manual/Automatic code generation
0% 100%
MM
Business
model
Design
model
Code
model
MM MM

MDA: PIMs and PSMs
MDA models
 PIM: Platform Independent Models
Formal specification of a system that abstracts away
technical detail
Example: Billing system expressed in UML
 Platform Description Models (PDMs)
e.g. of component constructs (CCM), of Eiffel, C#, EJB,
…
 PSM: Platform Specific Models
Expressed in terms of the specification model of the
platform
Example: Billing system expressed in "UML profile for
CORBA"

Basic MDE operations
PIM PSM Code
4
2 5
3
1
 OMG standards are specified in terms of a PIM and normally one or more PSMs,
all in UML or UML profiles or based on any other kind of MOF meta-model.
 The MDA defines consistent relationships across these models.
 It makes it easier to produce implementations on different platforms while
conforming to the same essential and precise structure and behavior of the
system. As a consequence, the business model may define business goals and
policies in a computation independent manner.

Some of the OMG successes
1. CORBA
2. IDL
3. IIOP
4. UML
5. MOF
6. XMI
7. CWM
8. SPEM
yesterday
today
tomorrow
OMA
MDA
?

UML 2.0 : not a language, but a
family of languages
 UML 2.0 Infrastructure RFP - - A
UML 2.0 RFP issued September 15,
2000 that is primarily concerned with
architectural alignment, restructuring
and extension mechanisms.
 UML 2.0 Superstructure RFP - - A
UML 2.0 RFP issued September 15,
the refinement and extension of UML
1.x semantics and notation.
 UML 2.0 OCL RFP - - A UML 2.0
RFP issued September 15, 2000 that is
primarily concerned with with defining
an OCL metamodel.
 UML 2.0 Diagram Interchange RFP -
- A UML 2.0 RFP issued March 2,
defining a metamodel for diagram
interchange using the XMI facility.
from "Will UML 2.0 Be Agile or
Awkward?" by Cris Kobryn
Main concern
is the
separation
of concerns

UML opened the road,
several roads indeed...
UML/MOF
OMT
Merise
SA/RT
ERD
SADT
DFD
etc.
Product
and
Process
models
+
Model
Driven
Engineering JSD
From Object-Oriented Programming
to
Model-Driven Software Engineering.

The initial roadmap: separation of
artifact and process aspects
Procedural ADM
OOADM
e.g. OMT
UML UPM
SPEM
>2001
07/200111/1997
Network of models
+ profiles
+ other MMs
+ specific processes
(RUP, IBM SI, etc.)
Method = notation + process + tools
Model
weaving
Unified Method: impossible

Models Everywhere
Business
modelBusiness
processes
Business
rules
Workflow
model
Test
model
User
model
Cost
model
Development
process
model
Design
model
Class
model Object
model
Dynamic
model
UseCase
model
Interaction
model
Resource
model
Agent
model
etc.
Performance
model
Business
objects

The software life cycle is populated with a lot of models
 The development software cycle is
populated with models
 Models are of unequal importance
 The model space is structured (composite
and atomic models)
 Models are related in a complex network
of production/consumption
separation/weaving, transformation, etc.
 The content of each model is defined
(constrained) by a corresponding meta-
model (ontology)
 The model space is constantly broadening
starting from the essential models
(Domain, Service, Resource)
 All models are not of equal importance
Requirement
model
Business
Object
model
Workflow
model
Business
rules
model
Business
process
model
Design
model
Deployment
model
Test
model
Performance
model
QoS
model
Execution
model
etc.
1 aspect = 1 model

Each model has different
characteristics
 A Smalltalk coding model only offers single inheritance, but
also explicit anonymous metaclasses.
 An Eiffel coding model has a different form of inheritance and
several extensions (contracts, etc.). It has also specific "client"
relations between classes.
 A Java (or C#) coding model has two notions of inheritance,
corresponding to the class and interface categories.
 A C# coding model allows cross-language inheritance
 A workflow model is built from basic tasks.
 A usage model contains the concepts of actors, use-cases and
several relations like specialization of use-cases.
 etc.

From contemplative to productive
+Applicant()
+ApplicantInfo()
+MakeApplication()
-companyName : CString
-experience : CString
-reference1 : CString
Applicant
+Person()
+PersonInfo()
-personID : unsigned long
-surname : CString
-givenName : CString
-middleInitial : char
-streetAddress : CString
-postCode : CString
-countryname : CString
-eMailAddress : CString
Person
-is taught by
1
-teaches
0..*
+CourseSession()
+CourseSessionInfo()
-courseSessionID : unsigned long
-courseDate : unsigned long
-courseID : unsigned long
-courseLocation : CString
CourseSession
+AppStatus()
+AppStatusInfo()
-statusCode : char
-statusName : CString
AppStatus
+CourseRegistration()
+CourseRegistrationInfo()
-registrationDate : unsigned long
-completionFlag : bool
-confirmedDate : unsigned long
CourseRegistration
+Test()
+TestInfo()
-testScore : unsigned long
Test
+Application()
+ApplicationInfo()
-productNr : unsigned long
-certificationLevel : unsigned long
-applicationDate : unsigned long
Application
+PermittedStatusChange()
+StatusChangeInfo()
-fromStatus : char
-toStatus : char
PermittedStatusChange
+ExamSession()
+ExamSessionInfo()
-examSession : unsigned long
-examlocation : CString
-examDate : unsigned long
ExamSession
-gives0..*
-is achieved1
-is made by
1
-makes
0..*
-allows change in
0..*
-has a
1..*
-is taken by1
-takes0..*
-is made by a1
-made a1..*
-is in1
-is filled by0..*
-uses
1
-is used in
0..*
-applies to a0..*
-is for a1
+Exam()
+ExamInfo()
-examID : unsigned long
-certificationLevel : unsigned long
Exam
+Employee()
+GetCurrentAge()
+EmployeeInfo()
-jobType : CString
-roomNr : unsigned long
-department : CString
-division : CString
-jobTitle : CString
-manager : unsigned long
-headsDept : CString
-headsDivision : CString
-mobileNr : CString
-birthDate : unsigned long
Employee
+registrationform()
RegistrationForm
-uses*
*
ApplicantApplicantList PersonList
findApplicant()
ApplicationRegForm
Applicant()
findPerson()
addPerson()
addApplication()
Application()
MakeApplication()
ApplicationList
class
sequence
Java
code
"from human-readable to computer-understandable"

Compare code-centric and
model-centric approaches
OMA
MDA
IDL  UML+OCL

Fragments of a UML meta-model
UML
not 1.4

Three stages in the evolution of modeling
techniques at OMG.
UML MOF
UMLaModel
aModel
MOF
UML
UML_FBO
aModel
PWG Workflow etc.
Common Warehouse
Metadata Interchange
Action language
(a) (b) (c)

OMG : the software bus and the
knowledge bus.
Cobol
CORBA, IDL, IIOP,...
Java
Workflow
MOF, UML, XML,...
UML
UPM
CWM
C#

Systems and models
A model M is a
simplified
representation of the
world, as a matter of
fact of only a part S
of the world called the
system.
M
S
isRepresentedBy
M0
(the world)
M1
(the modeling space)

Aspect-Oriented Modeling
Obviously a
given system
may have plenty
of different
models.
Each model
represents a
given aspect of
the system.
Ma
S
isRepresentedBy
M0
M1
Mb
Mc

Limited Substitutability Principle
 The purpose of a model is always to be able to answer some
questions in place of the system, exactly in the same way the
system itself would have answered similar questions.
 A model represents certain specific aspects of a system and
only these aspects.
 But how to make this assumption explicit, automatically
checkable, etc?

Various kinds of models
 Products and processes
 Legacy and components
 Static and dynamic
 Functional and non-functional aspects
 etc.

Systems and models
What is exactly this
relation?
Can we specify this
"aspect selection" with
precision?
How to combine
several such relations?
How to characterize
them?
M
S
isRepresentedBy
M0
(the world)
M1

Solution: Metamodel
S
M*
M
The correspondence between a model and a system
is explicitly and precisely defined by a metamodel.
sem

Ontologies and metamodels
For the theorician, this is an
ontology
For the IS practitioner, this
is a metamodel
A metamodel is a simple form
of an ontology
M
S
isRepresentedBy
M0
(the world)
M1

Ontology: definition
Gruber, T.G.
A Translation Approach to Portable Ontology Specifications
Knowledge Acquisition, V.5, N.2, (1993)
"A body of formally represented knowledge is based on a conceptualization: the
objects, concepts, and other entities that are presumed to exist in some area of interest
and the relationships that holds them.
A conceptualization is an abstract, simplified view of the world that we wish to
represent for some purpose.
An ontology is an explicit specification of a conceptualization. The term is borrowed
from philosophy, where an ontology is a systematic account of Existence. For
knowledge-based systems, what "exists" is exactly that which can be represented. When
the knowledge of a domain is represented in a declarative formalism, the set of objects
that can be represented is called the universe of discourse. This set of objects, and the
describable relationships among them, are reflected in the representational vocabulary
with which a knowledge-based program represents knowledge. Thus, we can define the
ontology of a program by defining a set of representational terms. In such an ontology,
definitions associate the names of entities in the universe of discourse (e.g. classes,
relations, functions or other objects) with human-readable text describing what the
names are meant to denote ..."

Meta-models and ontologies
 Ontologies bring:
Abstraction
Consensus and sharing

Ontologies
Normative consensus
Consensual norms
Because sometimes:
there are non-normative consensus
there are non-consensual norms

Layered ontologies
terminological
Concepts and Relations
e.g. UML diagrams
e.g. OCL statementse.g. How to draw a class?
presentation issues, etc.

Egyptian architecture
metamodel
model
"the real world"
metameta
model
The MOF (some kind of "top level ontology")
The UML metamodel and other MMs
Some UML Models and other Ms
Various usages of these models
M0
M1
M2
M3
[Inspired by IRDS,
CDIF, etc.]

MOF : some definitions
 The MOF is unique and self-
defined.
 In principle, the MOF should
be minimal.
 The MOF factorize all that
is common to all meta-
models, e.g.:
 Generating towards a given
middleware (.Net, Corba,
Java, etc)
 Transporting models and
metamodels
 Persistent support for
models and metamodels
(repository)
domain-specific
domain-independant

Multiple meta-models
MOF::Class
UML::Class
UML::Participant
Peter Smith
Java::Class
Java::Participant
Peter Smith

The Three Modeling Layers
the MOF
MMM
the UML
MM
a UML
model m
a particular
use of m
the SPEM
MM
the CCM
MM
another UML
model m’
another
use of m
Level M3
Level M2
Level M1
Level M0

The OMG/MOF Meta-Model Stack
Université de NANTES
M1, M2 & M3 spaces
M3
M2
M1
M2
M1
M2
M1 M1M1
- One unique Metametamodel (the MOF)
- An important library of compatible Metamodels
- Each of the models
is defined in the language of its unique metamodel

Direct relations between MMs
MOF
UML MM
CWM MMUSES
C2 C2
CWM
Model
C2
Drawing the global
picture

UML profiles
 A UML profile is a grouping construct for UML model
elements that have been customized for a specific
domain or purpose using extension mechanisms such
as stereotypes, tagged values and constraints. For
example, the UML Profile for CORBA RFP customizes
UML for specifying CORBA IDL.
 A metamodel defines a domain-specific language. A
profile is a variant of a metamodel. It allows to
define a dialect of a given language. There are a
dozen of UML profiles that are currently being
defined.

Abstract Syntax Systems Compared
MOF
The UML
meta-Model
A Specific
UML Model
A Specific
phenomenon
corresponding to
a UML Model
EBNF
Pascal Language
Grammar
A specific
Pascal Program
A specific
execution
of a Pascal
program
A XML
document
A XML DTD
Or Schema
A XML
document
A XML DTD
or Schema
Technology #2
(MOF + OCL)
Technology #3
(XML Meta-Language)
M3
M2
M1
KIF
Theories
Upper Level
Ontologies
Technology #4
(Ontology engineering)
[XMI=MOF+XML+OCL]
Model serialisation
Technology #1
(formal grammars
attribute grammars,
etc.)
+Description
Logics
+Conceptual
Graphs
+etc.
+Xpath, XSLT
+RDF, OIL, DAML
+etc.
:from contemplative
to productive.

Some technical spaces
model
mm
UML/MOF
program
grammar
Java
document
schema
XML
DBMS
SQL
etc
KBMS

Ex: Weaving geographical and
political aspects in XML
<gml:location>
<gml:Point>
<gml:coord>
<gml:X>1.0</gml:X>
<gml:Y>1.0</gml:Y>
</gml:coord>
</gml:Point>
</gml:location>
<gml:Polygon gid="810">
<gml:outerBounderyIs>
<gml:LinearRing>
<gml:coordinates>0.0,0.0 100.0,0.0 50.0,100.0 0.0,0.0</gml:coordinates>
</gml:LinearRing>
</gml:outerBoundaryIs>
</gml:Polygon>
<Bureaudevote>
<num>810</num>
<NbInscrits>870</NbInscrits>
<NbVotants>507</NbVotants>
<Ayrault%>70.72</Ayrault%>
<Harousseau%>20.44</Harousseau%>
</Bureaudevote>
Geographical map + political results per voting area
=
political
map

Model weaving
 XML technology offers tools
for document merging (Xlink,
Xpointer, etc.)
 It is also possible to perform
the weaving operation within
the model space and then to
project to the XML space
(SVG, GML, etc.)

T/xslt
Ex: Crossing the MOF to XML boundary
Ma/xmi
Ma
Mb/xmi
Mb
Abstract model
space.
Concrete model
space
(XML supported)
T

Various kinds of transformations
Ma Mb
MMab
Endogeneous
transformation
sem sem
Ma Mb
MMa
Exogeneous
transformation
sem sem
MMa
Tab Tab

Tooling the MDA : Sample
 Adaptive's Framework http://www.adaptive.com/
 France-Telecom Universalis http://universalis.elibel.tm.fr/
 Codagen Gen-it http://www.codagen.com/
 Codigo CodigoXpress http://www.codigoxpress.com/
 DSTC dMOF http://www.dstc.edu.au/Products/CORBA/MOF/
 Interactive Objects ArcStyler http://www.io-software.com/
 Kabira Business Accelerator http://www.kabira.com/
 Kennedy Carter iUML and iCCG http://www.kc.com/
 Metamatrix MetaBase http://metamatrix.com/
 NetBeans Meta Data Repository MDR http://www.netbeans.org/
 ONTOS ObjectSpark http://www.objectspark.com/
 ObjectRad Java Metadata Server http://www.objectrad.com/
 ObjeXion Software Netsilon http://www.netsilon.com/
 Project Technology BridgePoint/DesignPoint http://www.projtech.com/
 Secant Technologies ModelMethods http://www.modelmethods.com/
 Soft-Maint Scriptor & Semantor http://www.sodifrance.fr/
 Tata Research Development ADEX http://www.tcs.com/
 University of Berne MOOSE http://www.iam.unibe.ch/
and much more…

Part of the C#/DotNet MetaModel
Field
Constructor
Property
isReadable : Boolean
isWritable : Boolean
Member
name : String
Assembly
name : String
Method
TypedAttribute
MethodBase
visibility: String
isAbstract : Boolean
isFinal : Boolean
isStatic : Boolean
Type
qualifiedName : String
isAbstract : Boolean
visibility: String
isSealed : Boolean
namespace : String
0..1
0..*
owner
0..1
members
0..*
0..*
0..1
content
0..*
container
0..1
0..1
0..*
super
0..1
type
0..*
0..1
0..*
returnType
0..1
0..*
1
0..* type
1
0..*
Parameter
isIn : Boolean
isOut : Boolean
name : String
position : Integer
0..*
1
parameters
0..*
method
1
1
0..*
type 1
0..*

The Ycycle : weaving PIMs & PDMs
to produce PSMs
PIMs
(Platform
Independent
Models)
PSMs
(Platform
Specific
Models)
M
Merging/binding phase
PDMs
(Platform
Description
Models)
?
binding

MDA: beyond the buzzword
 Modern model engineering techniques are ready for prime time in software
engineering.They are based on:
 A four level architecture (3+1)
 A unique metametamodel (MOF),
 with transfer and exchange mechanisms
 with transformation mechanisms
 with standard projection mechanisms on a variety of middlewares (CORBA
first, Java and DotNet next, …)
 A growing collection of specialized meta-models (evolutive)
 Object metamodels (Java/EJB/J2EE, CLR, CCM, etc.)
 Legacy metamodels (Relational, CWM)
 Enterprise metamodels : Business objects, Healthcare, Transportation,
Process & Rules, and much more
 Product an process metamodels (e.g. workflow, RUP)
 Automatic and semi-automatic generation tools, from high abstraction
standardized models to various middleware platforms will progressively
appear in the coming years.

Conclusion
Model engineering is the future
of object technology
 As object and classes were seen in the 80's as "first class entities",
with libraries of several hundred of classes hierarchically organized,
models and metamodels are beginning to be considered alike in the
2000's.
 Libraries (lattices) of hundreds of metamodels (ontologies) of high
abstraction and low granularity are beginning to appear. Each such
metamodel may contains several hundreds of concepts and relations.
 Tools will be needed to work with these vast libraries of models and
metamodels.
 This will have a rapid impact on the daily work of the information
engineer.
 More research is urgently needed to bring together the people involved
in the theory and practice of model engineering (ontologists,
methodologists, software practitioners, information system builders,
database specialists, etc.).

AOP: the code as unique reference
Debugging
directives
Optimisation
directives
Synchronization
Exceptions
Executable
code
Algorithms
Organization
code
(#include, etc.)
preconditions
postconditions

The on-line separate models organization
(aspect-oriented software engineering)
Common BUS (e.g. CORBA or DotNet + UML + MOF + XMI)
Execution
model
Architecture
model
Deployment
model
Domain
model
Design
model
Test
model
Usage
model (Use
Cases)
Resource
model
First-class independent models and metamodels

Where are models coming from?
 Essential models (resource, business logic, service)
 Other development sources (exception handling, testing, user
behaviour, enforcing contracts, performance improvement,
deployment, security, authentification, concurrency
management, etc.),
 Legacy systems,
 Derived models,
 Executable code extraction (code is a model)
 Multiple other sources, like Just in Time Model Production
 etc.

Combining the power of meta-
modeling and metaprogramming
a C# program
execution
a C#
meta-model
a C#
model
read XMI
write XMI
[This may be the ultimate strategy
for modern software maintenance]
sem
Introspection at workThis is
a dynamic
model.

AOM: oxymoron or pleonasm?
 The central issue in AOSD is knowledge management (aspects + operations)
 AOP gives a key role to the code (executable code) for this representation
problem.
 As a consequence the problem of final mapping to executable code is solved
 But the problem of precise definition, capture and maintenance of the various
aspects is made more difficult
 On the contrary, MDA/MDE starts from the a priori of an independent and
homogeneous representation of aspects in non-executable "external spaces"
 The conceptual handling of separate aspects and operations on these aspects is
considerably simplified
 The practical handling of mapping to executable platforms (operationalization) still
requires considerable research and development efforts that will go much beyond
compiler technology and rewriting systems.
 From the point of view of representation systems, AOM is an oxymoron
 From the point of view of the problem to be solved (separation of
concerns), AOM is a pleonasm.
 There seems to be more place for cooperation than competition between
both approaches.

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