In this paper, we propose a new architecture for group communication middleware. Current group communication systems share some common features, despite the big differences that exist among them. We first point out these common features by describing the most representative group communication architectures implemented over the last 15 years. Then we show the features of our new architecture, which provide several advantages over the existing architectures: (1) it is less complex, (2) it defines a set of group communication abstractions that is more consistent than the abstractions usually provided, and (3) it can be made more responsive in case of failures.