Synchronous data-flow is a programming paradigm which has been successfully applied in reactive systems. In this context, it can be characterized as some class of static bounded memory data-flow networks. In particular, these networks are not recursively defined, and obey some kind of "synchronous" constraints (clock calculus). Based on Kahn's relationship between data-flow and stream functions, the synchronous constraints can be related to Wadler's listlessness, and can be seen as sufficient conditions ensuring listless evaluation. As a by-product, those networks enjoy efficient compiling techniques. In this paper, we show that it is possible to extend the class of static synchronous data-flow to higher order and dynamical networks, thus giving sense to a larger class of synchronous data-flow networks.

: In the reactive approach, system components are not supposed to execute at their own rate, but are instead driven by a logical common clock, defining global instants. The Reactive Object Model introduced in this paper, is an object based formalism matching the reactive paradigm. In this model, methods can be invoked using instantaneous non-blocking send orders, which are immediately processed (that is, processed during the current instant); moreover, a method cannot execute more than once at each instant. The Reactive Object Model is described and compared to the Actor Model; then a prototype language based on this model is introduced; finally its expressive power is shown on the example of a broadcast communication mechanism. Key-words: Actors, Concurrent Programming,Objects, Reactive Approach (R'esum'e : tsvp) Unite de recherche INRIA Sophia-Antipolis 2004 route des Lucioles, BP 93, 06902 SOPHIA-ANTIPOLIS Cedex (France) Telephone : (33) 93 65 77 77 -- Telecopie : (33) 93 65 77 ...

Systems made of distributed reactive processes communicating with shared variables are described. Execution of these systems is in two phases: first variables are written, then read. Couples of these two phases define system instants, and during one instant, all readers of a given shared variables read the same value. One thus get deterministic systems with a kind of shared variable coherency.