In DAI community, it is usually agreed that cooperation between reasoning agents needs explicit communication, and that this term of communication means more thant it means in traditional distributed systems. In this paper, we will discuss our proposal for an" Interaction Language" associated with" Interaction Protocols", inspired by the Speech Act Theory. We will demonstrate its use for the problem of the global control of a society of vision modules. The solution of this control problem will be presented through two experimental systems, namely VAP I'and MAGIC, the basic interacting modules (or agents) of which are respectively developped at Grenoble (LIFIA) and in Nancy (CRIN).