Kermeta - AbsoluteAstronomy.com

History

The Kermeta language was initiated by Franck Fleurey in 2005 within the Triskell team of IRISA

IRISA

The Institut de recherche en informatique et systèmes aléatoires is a joint computer science research center of CNRS, University of Rennes 1, INSA and INRIA, located in Rennes in Brittany...

(gathering researchers of the INRIA, CNRS, INSA and the University of Rennes

University of Rennes

The University of Rennes was a French university located in the city of Rennes. It was established by the union of the 3 faculties of the city in 1885. In 1969, it was divided in two new universities:* the University of Rennes 1...

1).

The Kermeta language borrows concepts from languages such MOF

Meta-Object Facility

The Meta-Object Facility is an Object Management Group standard for model-driven engineering. The official reference page may be found at OMG's website.- Overview :...

, OCL

Object Constraint Language

The Object Constraint Language is a declarative language for describing rules that apply to Unified Modeling Language models developed at IBM and now part of the UML standard. Initially, OCL was only a formal specification language extension to UML. OCL may now be used with any Meta-Object...

and QVT

QVT

QVT is a standard set of languages for model transformation defined by the Object Management Group .- Overview :...

, but also from BasicMTL, a model transformation language implemented in 2004 in the Triskell team by D. Vojtisek and F. Fondement. It is also inspired by the previous experience on MTL, the first transformation language created by Triskell, and by the Xion action language for UML

Unified Modeling Language

Unified Modeling Language is a standardized general-purpose modeling language in the field of object-oriented software engineering. The standard is managed, and was created, by the Object Management Group...

.

The name Kermeta is an abbreviation for "Kernel Metamodeling" and reflects the fact that the language is conceived as a core for (meta-)modeling. The Breton language

Breton language

Breton is a Celtic language spoken in Brittany , France. Breton is a Brythonic language, descended from the Celtic British language brought from Great Britain to Armorica by migrating Britons during the Early Middle Ages. Like the other Brythonic languages, Welsh and Cornish, it is classified as...

consonance of this name is an intentional reflection of the Triskell team's location in Britanny.

Kermeta, and its execution platform under Eclipse

Eclipse (software)

Eclipse is a multi-language software development environment comprising an integrated development environment and an extensible plug-in system...

is currently available under its version 1.4.1. It is open-source, under the Eclipse Public License

Eclipse Public License

The Eclipse Public License is an open source software license used by the Eclipse Foundation for its software. It replaces the Common Public License and removes certain terms relating to litigations related to patents....

Philosophy

Kermeta is a modeling and aspect oriented programming language. Its underlying metamodel conforms to the EMOF standard. It is designed to write programs which are also models, to write transformations of models (programs that transform a model into another), to write constraints on these models, and to execute them 1). The goal of this model approach is to bring an additional level of abstraction on top of the "object" level and thus to see a given system like a set of concepts (and instances of concepts) that form an explicitly coherent whole, which one will call a model.

Kermeta thus brings:

all the concepts of EMOF used for the specifications of a model.
a real concept of model, more precisely of model type (Jim Steel).
a concrete syntax that fits well to model and metamodel writing.
two paradigms: the object, and the model.
a bridge towards the Eclipse ECore formalism

Characteristics

The main characteristics of the Kermeta language are :

imperative
Imperative programming
In computer science, imperative programming is a programming paradigm that describes computation in terms of statements that change a program state...

: traditional structures of control
object-oriented: multiple inheritance, late binding
model-oriented: first-class concepts of associations and composition
aspect-oriented: integrate a simple but powerful weaver for simple meta-modeling tasks. Arbitrary complex weaving is achieved using a dedicated composer written in Kermeta. This allows to extend existing metamodel. Especially in order to add behavior to them by weaving behavioral semantic
Formal semantics of programming languages
In programming language theory, semantics is the field concerned with the rigorous mathematical study of the meaning of programming languages and models of computation...

(operational or translational).
design by contract
Design by contract
Design by contract , also known as programming by contract and design-by-contract programming, is an approach to designing computer software...

: operations support pre and post conditions, classes use invariants.
functional
Functional programming
In computer science, functional programming is a programming paradigm that treats computation as the evaluation of mathematical functions and avoids state and mutable data. It emphasizes the application of functions, in contrast to the imperative programming style, which emphasizes changes in state...

: functions and first class lambda-expressions
statically typed: genericity for the classes and the operations, function types...
complete introspection
Type introspection
In computing, type introspection is a capability of some object-oriented programming languages to determine the type of an object at runtime. This is a notable capability of the Objective-C language, and is a common feature in any language that allows object classes to be manipulated as first-class...

: the complete model of the program is available during execution.

Syntax

The curious reader will find further information on the Kermeta website.

Example



 package fsm;



 require kermeta



 using kermeta::standard



 class FSM

 {

    attribute ownedState : set State[0..*]#owningFSM

    reference initialState : State[1..1]

    reference currentState : State



    /**

     * Print the FSM on the standard output

     */

    operation printFSM is do

        self.ownedState.each

        { s |

            stdio.writeln("State : " + s.name)

            s.outgoingTransition.each

            { t |

                stdio.writeln("  Transition : " + t.source.name +

                "-(" + t.input + "/" + t.output + ")->" + t.target.name)

            }

        }

    end

 }



 class State {

    attribute name : String

    reference owningFSM : FSM#ownedState

    attribute outgoingTransition : set Transition[0..*]#source

    reference incomingTransition : set Transition[0..*]#target

 

    operation step(c : String) : String is do

        // Get the valid transitions

        var validTransitions : Collection

        validTransitions :=    outgoingTransition.select { t | t.input.equals(c) }

        // Check if there is one and only one valid transition

        if validTransitions.empty then raise "No Transition!" end

        if validTransitions.size > 1 then raise "Non Determinism" end

        // fire the transition

        result := validTransitions.one.fire

    end

 

 

 }



 class Transition

 {

    reference source : State[1..1]#outgoingTransition

    reference target : State[1..1]#incomingTransition

    attribute output : String

    attribute input : String

 

    operation fire : String is do

        // update FSM current state

        source.owningFSM.currentState := target

        result := output

    end

 }

External links