\paragraph*{R\'esum\'e :}
Cet article pr\'esente la conception d'une plateforme de {\em mod\'elisation},
{\em classification} et {\em exp\'erimentation} de
{\em programmation concurrente par objets}.
Notre motivation est d'offrir un outil qui peut
aider \`a d\'ecrire, analyser, comparer, combiner, exp\'erimenter,
et enfin utiliser diff\'erents formalismes
(mod\`eles de calcul, langages de programmation,
strat\'egies de synchronisation...)
de programmation concurrente par objets.
Cette plateforme, nomm\'ee {\em Actalk}, est implant\'ee et {\em int\'egr\'ee}
\`a l'environnement de programmation {\em Smalltalk-80}.

Actalk se fonde sur l'existence
d'un {\em noyau} qui mod\'elise la s\'emantique de base
(c'est-\`a-dire des {\em objets actifs} et s\'equentiels
communicant par {\em envoi de messages asynchrone} et unidirectionnel).
Ce noyau se compose d'un ensemble de classes ainsi que de {\em m\'ethodes
param\`etres} associ\'ees destin\'ees \`a \^etre red\'efinies.
Diff\'erentes {\em extensions}, d\'efinies comme sous-classes des
classes du noyau, simulent divers formalismes
de programmation concurrente \`a objets.
Elles expriment diff\'erents mod\`eles d'{\em activit\'e}
(s\'equentiel, concurrent...),
de {\em communication} (synchrone, \`a r\'eponse anticip\'ee...),
et de strat\'egies de {\em synchronisation} d'activation des requ\^etes.

Dans cet article nous d\'ecrivons les motivations
et les choix de conception de la plateforme Actalk
ainsi que l'architecture de sa derni\`ere version.
Les choix de repr\'esentation, d\'ecomposition
et de {\em param\'etrisation}
de l'architecture sont plus particuli\`erement discut\'es dans cet article.
Nous r\'esumons ensuite les diff\'erents formalismes
actuellement mod\'elis\'es comme sous-classes/extensions
des classes composant le noyau.
Nous pr\'esentons enfin un exemple d\'evelopp\'e pour illustrer
l'expressivit\'e de cette plateforme \`a travers
la {\em combinaison} de deux formalismes
de synchronisation d\'edi\'es \`a la programmation concurrente
par objets.
Enfin, avant de conclure, nous discuterons bri\`evement
les int\'er\^ets de m\^eme que les limites de la plateforme,
puis r\'esumerons ses diff\'erents d\'eveloppements
ainsi que les travaux similaires.

\paragraph*{Mots-cl\'es :}
mod\'elisation, classification, programmation concurrente \`a objets,
plateforme, Smalltalk-80.

\paragraph*{Abstract :}
This paper describes the design of a testbed for 
{\em modeling}, {\em classifying} and {\em experimenting} with
{\em object-oriented concurrent programming} (OOCP in short).
We aim at providing a tool to help
describing, analyzing, comparing, combining, experimenting,
and using various OOCP formalisms
(computation models, programming languages,
synchronization strategies\ldots).
This testbed, named {\em Actalk}, is implemented and {\em integrated}
within the {\em Smalltalk-80} programming environment.

Actalk is based on some {\em kernel} which models basic OOCP
semantic (i.e., serial {\em active objects}
communicating through unidirectional {\em asynchronous message send}).
This kernel is composed of a set of classes and
their associated {\em parameter methods} intended to be further redefined.
Various {\em extensions}, defined as sub-classes of the kernel classes,
simulate various OOCP formalisms.
They specify different models of {\em activity}
(serial, concurrent\ldots),
{\em communication} (synchronous, with eager reply\ldots),
and {\em synchronization} strategies (for controlling activation of requests).

In this paper we first discuss motivations and design decisions
for the Actalk testbed.
We then describe the architecture of the new version of Actalk.
Representation choices as well as decomposition and {\em parameterization}
of the architecture are specially discussed in this paper.
We summarize various formalisms
which have been actually modeled/simulated as sub-classes/extensions
of the kernel classes.
We finally introduce and detail one example
{\em combining} two synchronization formalisms
in order to show the expressivity of the platform.
Before concluding we briefly discuss the merits and limitations
of the platform and we summarize its various developments
as well as related work.

\paragraph*{Keywords :}
modeling, classifying, object-oriented concurrent programming,
testbed/platform, Smalltalk-80.