Modeling and meta-modeling presentation at LTH, Sweden

Modeling & meta-modeling

SERG, LTH – May 15, 2012

By: Saïd Assar1,2
(1) Telecom Ecole de Management, Department of Information Systems, Evry, France
(2) Centre de Recherche en Informatique, University of Paris 1 La Sorbonne, France

1. Introduction & background
• Initial research work on CASE design, model
transformation, code generation (PhD, 1995)

 Different research topics:
 Methods and tools for SE & ISE
 Technology adoption & diffusion

SERG@LTH – May 15, 2012 2

1. Introduction & background (cont'd)

• INSTITUT TELECOM: 4 leading schools in engineering
and management
Telecom Ecole de
Management
Telecom Bretagne Telecom Sud Paris

Telecom Paris



 Since 1999, long-term research collaboration with CRI at
Paris 1 Sorbonne



Objectives
 Overview of modeling and meta-modeling in IS & SE
 Present fundamental issues in modeling & meta-
modeling
 Overview of available tools for meta-modeling
 Sketch some actual research problems in meta-
modeling



Agenda
1. Introduction & background
2. About models
3. About meta-models
4. Computerized tools for meta-modeling
5. A meta-modeling application: model transformation
6. Behavior meta-modeling
7. Conclusion


2. About models
"A model (M) for a system (S) and an observer (O) is any kind of representation
which can help O in answering questions about S"

Descriptive
models

Observer

Prescriptive
models


2. About models (cont'd)
"A model (M) for a system (S) and an observer (O) is any kind of representation
which can help O in answering questions about S"
 A model is an abstraction
 A model is a reduction
 A model helps in better understanding the real world object/artifact
 A model is built using some kind of notation (formal and/or graphical)
 A model is the result (i.e. the product) of some specific activity (i.e. the modeling
process)
 Modeling is an essential activity in engineering
 Modeling is deeply related to design
 Models are essential for reasoning on the artifact being engineered
 Models are artifacts, i.e. they can also be modeled


Models and modeling in computer science
 What is modeled is information about concrete and abstract objects, relations,
links, events, operations, actors, roles, …
 Classification is an essential facet in modeling
 Models are constructed using modeling languages
 Information models have specific properties (i.e. instantiability, executability)

Selling an object

An airplane ticket
An official document
(car registration)
SERG@LTH – May 15, 2012 10

2. What is a model ? (cont'd)
Examples of models in computer science (1)
Conceptual data model name number location

fname minit lname 1
salary
N works for department
name sex address
1 number of
startdate employees
ssn 1
employee controls
1 manages
bdate
N
supervisor hours N
degree supervisee
1 M
supervision works on project

dependents of name number location

N

dependent

name sex birthdate relationship
SERG@LTH – May 15, 2012 11

Physical DB model

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Informal process model

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More precise process
model (UML)

SERG@LTH – May 15, 2012 14

More formal
process model
(BPMN)

SERG@LTH – May 15, 2012 15

Strictly formal process model (Petri net)

SERG@LTH – May 15, 2012 16

Executable web-service based process model (BPEL)

SERG@LTH – May 15, 2012 17

Feature models to capture systems variability

Example 1

Example 2
SERG@LTH – May 15, 2012 18

Open problems in modeling
 What is the quality of a model and how to evaluate it
 How to validate a model
 How to transform a model from one form to another
 How to link and integrate complementary models
 How to deal with model evolution
 How to create models (i.e. modeling process)
 What are the best usages of models
 What are the best/most adequate modeling languages
 How to express constraints that can't be directly represented
 How to create modeling languages that are adequate, relevant, efficient, …
…
Model engineering
Model driven engineering

SERG@LTH – May 15, 2012 19

3. About meta-models
Definition
• As model is an engineering artifact, it can be modeled

• Meta-models are formal representations of models (i.e. models of models)

• They are built using a (meta-) modeling language

• Meta-models generally describe structural properties of models, while behavioral
and semantic properties are expressed differently

• Meta-models formalize knowledge about modeling languages, i.e. abstract syntax
=> The modeling language is seen as instances of concepts in the meta-model

SERG@LTH – May 15, 2012 21

3. About meta-models (cont'd)
Examples (1)
• Entity/Relationship meta-model (self description)

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Examples (2)
• A simple process meta-model (E/R style)

Source: Hanns-Alexander Dietrich, Exercice 1 Meta-modelling, European Research Center for Information
Systems, Information Modelling Summer Term 2012.
SERG@LTH – May 15, 2012 23

Examples (2)
• A simple process meta-model (E/R style)

Source: Hanns-Alexander Dietrich, Exercice 1 Meta-modelling, European Research Center for Information
Systems, Information Modelling Summer Term 2012.
24

Examples (3)
• An extract of the OMG SPEM meta-model (UML)

SERG@LTH – May 15, 2012 25

Related concepts (1)
• Language syntax definition (a toy language)
<postal-address> ::= <name-part> <street-address> <zip-part>
<name-part> ::= <personal-part> <last-name> <opt-suffix-part> <EOL>|<personal-part> <name-part>
<personal-part> ::= <first-name> | <initial> "."
<street-address> ::= <house-num> <street-name> <opt-apt-num> <EOL>
<zip-part> ::= <town-name> "," <state-code> <ZIP-code> <EOL>
<opt-suffix-part> ::= "Sr." | "Jr." | <roman-numeral> | ""
<last-name> ::= [A-Z|a-z]
<first-name> ::= [A-Z|a-z]

first-name

initial
first-name-part
initial-part

personal-part opt-apt-num
1,1 street-num
component-p house-num
suffix-part
street-address-part
last-name Town-name
1,N
state-code
postal-address Zip-part
ZIP-code
SERG@LTH – May 15, 2012 26

Related concepts (2)
• Programming language syntax definition (C language)

 C language abstract syntax can be easily defined as a meta-model

SERG@LTH – May 15, 2012 27

Where does meta-modeling come from?
• Artificial intelligence (i.e. frame concept, Smalltalk, ObjVLisp1)
• Databases (i.e. meta-database)
• Object oriented modeling (i.e. Classes are objects too => MetaClasses, PowerTypes2)
[2] Mili, H., Pachet, F., Benyahia, I., Eddy, F.: Metamodeling in OO: OOPSLA’95 workshop
summary. Addendum to the proceedings of the 10th annual OPPSLA conference (OOPSLA’95).
ACM, New York, USA, pp. 105–110 (1995).

[1] Cointe, Pierre: Metaclasses are first class: The ObjVlisp
Model. SIGPLAN Notices. 22(12), 156–162 (1987).

SERG@LTH – May 15, 2012 28

What for?
• Better understanding and communicating about a modeling language

• Reasoning on its structure, its semantics and its usage

• Comparing and evaluating modeling languages

• Design of new modeling languages

• Design and implementation of MDE approaches

• Design and implementation of new methods
(i.e. method engineering)

Henderson-Sellers, Brian: Method engineering for OO systems
SERG@LTH – May 15, 2012 development. Communication of the ACM. 46(10), 73–78 (2003). 29

The instantiation problem (1)
• Meta-modeling is a specific form of modeling …

• However, if Class instances are Objects, what are the instances of MetaClasses ?

 Purely conceptual meta-models (i.e. no instantiation)
 Manual instantiation (i.e. translation/transformation based)
 Direct instantiation using a specific meta-modeling language

SERG@LTH – May 15, 2012 30

• Manual instantiation to build an E/R repository

CREATE TABLE EntityType (EntityName, …)
CREATE TABLE RelationshipType (RelationName, … )
CREATE TABLE RelationLinkEntities(EntityName, RelName, cardinality, …)
CREATE TABLE Attributes( … )
…

SERG@LTH – May 15, 2012 31

•The meta-
modeling language
issue

Source: ibid, Hanns-Alexander Dietrich, 2012

SERG@LTH – May 15, 2012 32

• Meta-modeling frameworks and languages: Meta Object Facility (MOF) by OMG

=> Strict instanciation
SERG@LTH – May 15, 2012 33


Source: OMG

SERG@LTH – May 15, 2012 34


SERG@LTH – May 15, 2012 35

• Meta-modeling frameworks and languages: ISO/IEC 24744 standard (Software
Engineering Metamodel for Development Methodologies)

• Pbs:
– How to simultaneously create a generalization link AND an instantiation link
– How to a define Class attributes
– How to cross the strict instantiation levels

Task CodingTask T1
instance instance
+ TaskCategory TaskCategory: Coding + TaskDuration:10d
+ TaskDuration TaskDuration: ?

• Proposal: Powertypes & Clabject
– A Clabject is a combination of an Object and a Class
– A Powertype is the description of a Clabject at the type level
SERG@LTH – May 15, 2012 36

• Meta-modeling frameworks and languages: ISO/IEC 24744 standard (Software
Engineering Metamodel for Development Methodologies)

Source: Henderson-Sellers, B., Gonzalez-Perez, C.: The
rationale of powertype-based metamodelling to underpin
software development methodologies. Proceedings 2nd
Asia-Pacific conf. on Conceptual modelling - Volume 43. pp.
7–16. Australian Computer Society, Inc. (2005). 37

• Meta-modeling frameworks and languages: deep instantiation

• Proposal:
– Add an indicator (potency) of the abstraction level at which the attribute is to
be instantiated

Task CodingTask T1
instance instance
+ TaskCategory1 TaskCategory: Coding + TaskDuration:10d
+ TaskDuration0

SERG@LTH – May 15, 2012 38

4. Computerized tools for
meta-modeling

MetaEdit (1)
• A meta-CASE tool for automatic customization of CASE tools
• Result of research project at Jyväskyla (K. Lyytinen, M. Rossi, S. Kelly et al. - 1990')
• Actually commercialized by MetaCASE
• Targeted towards Domain Specific Modeling

Meta-model definition Model definition

(Executable)
Generate code

SERG@LTH – May 15, 2012 40

4. Computerized tools for meta-modeling (cont'd)
MetaEdit (2)
• Meta-modeling language: GOPRR
• Graph
• Object
• Property
• Relationship
• Role

SERG@LTH – May 15, 2012 41

MetaEdit (3)
• Meta-editing functionalities

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MetaEdit (4)
• Customized editor

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MetaEdit (5)
• MERL: A scripting language for generating code (i.e. flow of characters)

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MetaEdit (6)
• Example in MERL for generating SQL code from E/R schema

SERG@LTH – May 15, 2012 45

MetaEdit (7)
• A detailed Domain Specific example

Source:
http://www.metacase.com/cases/phone_ex
ample.html

SERG@LTH – May 15, 2012 46

Conceptbase (1)
• A deductive database supporting object-centered TELOS modeling language
• Result from research project DAIDA (J. Mylopoulos, M. Jarke et al. - 1990')
• Continued as an open source project (M. A. Jeusfled)
• Targeted towards Model Engineering

TELOS modeling language
• Any element (class, object, attribute, link, constraint … ) is internally represented as
a predicate in a deductive DB
• Attributes are first order objects i.e. they can have properties
• Attributes correspond to links between two elements
• Any object can be instantiated
 Multiple instantiation ('Paul' in 'Employee' and 'Paul' in 'Student')
 Multiple levels of instantiation
 Multiple Generalisation/Specialisation (i.e. heritage)
 Generalisation/Specialisation can co-exist with instantiation

SERG@LTH – May 15, 2012 47

Conceptbase (2)
• Model llustration
Person in Class with Employee isA Person with
attribute attribute
ID: Integer; function: String
name:String end
end
Student isA Person with
Client isA Person with attribute
attribute age:Integer
reduction:Real end
end

SERG@LTH – May 15, 2012 48

Conceptbase (3)
• Model illustration
John in Student, Employee, Client with
ID
id_john: 44555
name
name_j: "John Legrand"
reduction
r1: 30.0
function
f1: "Sale manager"
age
age1: 24
end

Client with constraint
reduction_OK:
$ forall c/Client x/Real (c reduction x) ==> (x>=5.0) $
end
QueryClass AllPeople isA Person with
constraint
Allpeople_c: $ exists s/String (this nom s) $
end 49

Conceptbase (4)
• Meta-model illustration

SERG@LTH – May 15, 2012 50

5. A meta-modeling application:
model transformation

5. A meta-modeling application: model transformation
Transformation framework
• Transformation are expressed as declarative rules defined at the meta-model level

Source: Freddy Allilaire, Frédéric Jouault, Families to Persons - A simple illustration of model-to-model
transformation, ATLAS group, INRIA & University of Nantes, France

SERG@LTH – May 15, 2012 52

5. A meta-modeling application: model transformation (cont'd)

Transformation example (1)
• This is a toy example to transform two models

Transforming this … … into this.

… …
Family March Mr. Jim March
Father: Jim Mrs. Cindy March
Mother: Cindy Mr. Brandon March
Sons: Brandon Mrs. Brenda March
Daughters: Brenda … other Persons
… other Families

SERG@LTH – May 15, 2012 53



What is “Families”:
A collection of families. Family March
Father: Jim
Each family has a name and is composed Mother: Cindy
of members: Sons: Brandon
A father Daughters: Brenda
Family Sailor
A mother Father: Peter
Several sons Mother: Jackie
Sons: David, Dylan
Several daughters Daughters: Kelly
Each family member has a first name.

familyFather father
Family 0..1 1 Member
familyMother mother
0..1 1
familySon sons
lastName : String firstName : String
0..1 *
familyDaughter daughters
0..1 *
SERG@LTH – May 15, 2012 54



 The same model can be described
as BNF syntax

<Families> ::= <One-family> | <Family> ";" < Families>
<Family> ::= "Family :" <lastName> <Father-part> <Mother-part> <Sons-part> <Daughters-part>
<Father-part> ::= "Father: " <firstName> | ""
<Mother-part> ::= "Mother: " <firstName> | ""
<Sons-part> ::= "Sons: " <Sons-list> | ""
<Daughters-part> ::= "Daughters: " <Daughters-list> | ""
<Sons-list> ::= <firstName> | <firstName> "," < Sons-list>
<Daughters-list > ::= <firstName> | <firstName> "," < Daughters-list >
<firstName> ::= [A-Z][a-z]+
<lastName> ::= [A-Z][a-z]+

SERG@LTH – May 15, 2012 55



 Definition of the source model in
KM3 (EMOF)

package Families {

class Family {
attribute lastName : String;
reference father container : Member oppositeOf familyFather;
reference mother container : Member oppositeOf familyMother;
reference sons[*] container : Member oppositeOf familySon;
reference daughters[*] container : Member oppositeOf familyDaughter;
}

class Member {
attribute firstName : String;
reference familyFather[0-1] : Family oppositeOf father;
reference familyMother[0-1] : Family oppositeOf mother;
reference familySon[0-1] : Family oppositeOf sons;
reference familyDaughter[0-1] : Family oppositeOf daughters;
}

}

package PrimitiveTypes {
datatype String;
}

SERG@LTH – May 15, 2012 56



package Persons {
 Definition of the target model in
KM3 (EMOF)
abstract class Person {
attribute fullName : String;
Person
}
fullName
class Male extends Person { }

class Female extends Person { }

}
Male Female
package PrimitiveTypes {
datatype String;
}

SERG@LTH – May 15, 2012 57


This is a function defined
by the engineer
(definition not shown)
 Definition of transformation rules

rule Member2Female { -- Idem
from
s : Families!Member {(s.isFemale())
rule Member2Male
to from
t : Persons!Female Families!Member (not s.isFemale())
s : (
fullName <- s.firstName + ' ' + s.familyName
to
) t : Persons!Male (
} fullName <- s.firstName + ' ' + s.familyName
)
SERG@LTH – May 15, 2012 } 58


First, create an ATL project
 ATL tool interface

Next, define the ATL
transformation

Families:
IN:
Name of the
Name of the
source metamodel
source model in
in the
the transformation
transformation

OUT: Persons:
Name of the target Name of the target
model in the metamodel in the
transformation transformation

SERG@LTH – May 15, 2012 59


 ATL tool interface

Last, apply the transformation meta-program on input data

SERG@LTH – May 15, 2012 60

6. Behavior meta-modeling
Context & problem formulation
• Behavior perspectives are generally missing in software engineering
meta-models
Important knowledge about modeling languages is lacking
Essential for tools designers and method engineers
For a process modeling language, "behavior" perspective inquire
on its executable/operational semantics

Research goal
• How to express the operational semantics for a modeling language?
• How to design and build enactment engines for a given modeling
language?
 Maintainability and portability are central issues
SERG@LTH – May 15, 2012 62

6. Behavior meta-modeling (cont'd)
Methodological approach and expected results
• Problem formulation and analysis [INFORSID 2011, ICSOFT 2011]
• An exploratory study based on experimentation with MetaCASE
• A proposal for a new meta-modeling language to capture operational
semantics
 Instantiation problem
 An MDE approach for defining a generic approach to defining and
enacting a process modeling language

SERG@LTH – May 15, 2012 63

Methodological approach and expected results (1)

Step 1: structure
meta-model

Step 2: add the engine
architecture

SERG@LTH – May 15, 2012 64

Step 3: define the behavior using an event-oriented modeling language (ongoing work)

SERG@LTH – May 15, 2012 65

Step 4: transform the meta-models into an executable architecture based on the
publish/subscribe pattern (ongoing work)

SERG@LTH – May 15, 2012 66

6. Conclusion
• Models are essential artifacts in IS & SE
• Modeling languages design and development is an active field of research
• No well established and recognized standard for meta-modeling
• Tool support is complicated
• … OMG's MOF and IBM Eclipse emerge as "market" leaders for UML & Java
• MetaEdit: leader for DSM engineering tools
• Conceptbase: most powerful and theoretically sound modeling language
• Semantics for process meta-models still to be defined
• Beyond DSM, few empirical studies on meta-modeling applications

SERG@LTH – May 15, 2012 68

References and links
References
• Atkinson, C., Kühne, T.: The Essence of Multilevel Metamodeling. In: Gogolla, M. et Kobryn, C. (éd.) «UML»
2001 — The Unified Modeling Language. Modeling Languages, Concepts, and Tools. LNCS, vol.2185, pp. 19-
33. Springer, (2001).
• Atkinson, C., Kuhne, T.: Model-driven development: a metamodeling foundation. IEEE Software. 20(5), 36
- 41 (2003).
• Henderson-Sellers, B., Gonzalez-Perez, C.: A comparison of four process metamodels and the creation of a
new generic standard. Info. and Software Technology. 47(1), 49-65 (2005).
• Kelly, S., Tolvanen, J.-P.: Domain-specific modeling: enabling full code generation. Wiley-Interscience: IEEE
Computer Society, Hoboken, N.J. (2008).
• Henderson-Sellers, B., González Pérez, C.A.: Metamodelling for software engineering. John Wiley,
Hoboken, NJ (2009).
• Gargantini, A., Riccobene, E., Scandurra, P.: A semantic framework for metamodel-based languages.
Automated Software Engineering. 16(3-4), 415-454 (2009).
• Jeusfeld, M., Jarke, M., Mylopoulos, J.: Metamodeling for method engineering. The MIT Press, (2009).
• Sprinkle, J., Rumpe, B., Vangheluwe, H., Karsai, G.: Metamodelling: State of the Art and Research
Challenges. In: Giese, H., Karsai, G., Lee, E., Rumpe, B., et Schätz, B. (éd.) Model-Based Engineering of
Embedded Real-Time Systems. LNCS, vol.6100, pp. 57-76. Springer, Berlin/Heidelberg (2011).
Links
• MOF homepage: http://www.omg.org/mof/
• ISO/IEC 24744:2007 (Software Engineering -- Metamodel for Development Methodologies):
http://www.iso.org/iso/catalogue_detail.htm?csnumber=38854
• OPEN (Object-oriented Process, Environment and Notation) : http://www.open.org.au/
• Metacase: http://www.metacase.com/
• Conceptbase: http://conceptbase.sourceforge.net/
• Kermeta: http://www.kermeta.org
69

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Modeling and meta-modeling presentation at LTH, Sweden