the orchestra of multiple model repositories sergejs kozlovičs sergejs.kozlovics@lumii.lv research...

The Orchestra ofMultiple Model Repositories

Sergejs Kozlovičssergejs.kozlovics@lumii.lv

Research Laboratory of Modeling and Software TechnologiesInstitute of Mathematics and Computer Science, University of Latvia

The ``Orchestra'' Metaphor

Orchestra:

• multiple musical instruments

• playing simultaneously

002Research Laboratory of Modeling and Software TechnologiesInstitute of Mathematics and Computer Science, University of Latvia

Orchestra:

• multiple model repositories

• accessed simultaneously(inter-repository links are possible)

Orchestra:

• multiple model repositories

• accessed simultaneously(inter-repository links are possible)

Meta-s* a publication

* a newspaper

* The San Francisco Chronicle

* the May 18 edition of the

The San Francisco Chronicle

* my copy of the May 18 edition of the

The San Francisco Chronicle * my copy of the May 18 edition of the

The San Francisco Chronicle as it was when

I first picked it up (as contrasted with my copy as it

was a few days later: in my fireplace, burning)002Research Laboratory of Modeling and Software Technologies

Institute of Mathematics and Computer Science, University of Latvia

The "Gödel, Escher, Bach" book

by Douglas Hofstadter

MOF Meta-Levels (Linguistic)

Artifacts are organized into three layers:

• the meta-metamodel;

• metamodels conforming to the meta-metamodel;

• models conforming to some particular metamodel.

The Three-Level Conjecture(I. Kurtev and J. Bézivin)

The Three-Level Conjecture(I. Kurtev and J. Bézivin, 2005)

Artifacts are organized into three layers:

• the meta-metamodel;

• metamodels conforming to the meta-metamodel;

• models conforming to some particular metamodel.

The meta-metamodel is able to describe itself.

MOF Meta-Levels (Linguistic)

UML metamodel

UML model

conforms to

Technical Spaces(I. Kurtev, J. Bézivin, and M. Aksit; 2002, 2005)

UML metamodel

UML model

conforms to

MOF TS

OWL classes

OWL individuals

OWL DL

conforms to

RDF/OWL TS

ER-model (DB schema)

DB rows

DB system tables

conforms to

Relational DB TS

Technical Spaces (cont.)(I. Kurtev, J. Bézivin, and M. Aksit; 2002, 2005)

XML schema(.xsd)

XML document

XML metaschema

(XSD.xsd)

conforms to

XML TS

Java grammar

Java program

conforms to

Grammarware TS

Why different technical spaces?

• One TS can be more suitable than another

• Reusing skills and knowledge of a familiar TS

• A capability not available in a desired TS can be borrowed from another TS

TS interoperability

• Offline solution: using projectors and extractors (B´ezivin et al.)

• “Online” (On-the-fly) solution: this paper!o No deep copying of the data is required!

Problem 1: Numerous different repositories

See Table 1 in the paper!

Repositories

See Table 1 in the paper!

MOF TS:• EMF• CDO• MDR (NetBeans)• Enchanced Model

Repository• MetaMart Metadata

Repository• JR• ...

Repositories

The solution is a univeral Repository Access API, RAAPI• tda.lumii.lv/raapi.html

Problem 2: Ontological meta-levels

Ontological meta-levels

Meta-Levels (Ontological)

A meta-metamodel that supports infinitely many ontological meta-levels (used by the JR repository):

OWL Full also supports infinitely many ontological meta-levels.

Shostaks' conjecture

It is difficult for a human to think at more than two meta-levels at a time.

Still, it is pretty easy for a human to focus on any two adjacent meta-levels.

Shostaks' conjecture

It is difficult for a human to think at more than two meta-levels at a time.

Still, it is pretty easy for a human to focus on any two adjacent meta-levels.

Agris Šostaksat SOFSEM 2012

We divide the repository into two parts:

• M3 contating the meta-metamodel;

fixed for a particular repository/technical space;

• all other data (either M2+M1 or multiple ontological meta-levels)

Dealing with Šostaks' conjecture

• RAAPI is designed to work with any two adjacent meta-levels• Switching between levels and mixing them is possible by, e.g.,

passing a reference to a class when a reference to an object is expected.

The Idea

• The kernel represents all repositories as one big virtual repository.

• The kernel substitutes native references (integers) of each repository by globally unique proxy references.

• Inter-repository links are stored in the pivot repository.

Kernel Metamodel (the essence)

ProxyReferencedomesticReference:int64proxyReference:int64

Kernel

Repositoryurl:string

InterDirectedLink InterAttributeValuevalue:string

InterDirectedAssociationtargetRole:stringtargetCardinality:stringisComposition:Boolean

PackagesimpleName:stringnameInRepo:string

0..1 mounted Repository

1 mountPoint

pivot Repository

outgoingLinktarget Object

ingoingLink

source Object

0..1inverse

asso- cia- tion object

attribute

interSuperClass

interSubClass

outgoing Association

sourceClass1

ingoing Association

1 targetClass

inverse

0..1parent

*child

rootPackage

1associated Repository

RAAPI call example: createLink()

createLink(obj1_ref, obj2_ref, association_ref);

• If all proxy references point to the same repository, the call is forwarded to this repository.

• Otherwise, an inter-repository link is created and stored in the pivot repository.

Organizing repositories

• Unix file system directory tree:

/mnt/c

/mnt/d

/media

/media/cdrom

/etc002Research Laboratory of Modeling and Software Technologies

Institute of Mathematics and Computer Science, University of Latvia

mount points

• Package tree (~ UML package tree):

Package1

Package2

Package2::SubPackage

Package3

Package4

• Use “MountPoint::ClassName” to access a class in a mounted repository

mount points

Rootpackage

New repositorySubP

Problem 3:Manipulating the packages

How to merge packages?

I.e., when working with class Package1::A, objects and properties of Package2::A are also taken into a consideration.

Virtual repositories

Rootpackage

Virtual repositorySubP

Relies on data from somewhere else (or, invents data)

Rootpackage

Relies on data from somewhere else

Rootpackage

Relies on data from somewhere else

On-the-flymodeltransformation

Use cases for virtual repositories

Views on metamodels

Rootpackage

Basemetamodel

Volatile repository

Rootpackage

Virtual repository(stores its content

In RAM)

Volatilerepository

Virtual merge

Virtual repositoryimplementing

“merge”

Derived (calculated) associations and properties

A B A B

Virtual repositorycomputes

the association

A B A B

Virtual repositorycomputes

the association

Finally, we just need to virtually merge these two packages!

Virtual copy

P Virtualrepository

P(old data)

Virtualrepository

Virtual copy

P Virtualrepository

P(old data)

Virtualrepository

Δ2Δ1

Thank you!Děkuji!

The Orchestra ofMultiple Model Repositories

sergejs.kozlovics@lumii.lv

the orchestra of multiple model repositories sergejs kozlovičs sergejs.kozlovics@lumii.lv research...

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