Composing multiple-client-multiple-server synchronizations

A considerable number of language mechanisms have been proposed during recent years, to specify and implement concurrent object-oriented programs. The major concern of these proposals is to design an expressive language that provides extensible concurrent processing and synchronization features. Almost all these efforts, however, have focused on the multiple-client-single-server model where each server determines its synchronization semantics without cooperating with other objects. We believe that object-oriented concurrent languages must not only support a single-server model, but cooperatively synchronizing servers as well. We refer to this as multi-server synchronization. We first classify multi-server synchronization into five categories. The intention is to define a framework for evaluating current approaches and identifying the requirements for designing new languages. In addition, we present a composable multi-server synchronization technique, adopting the concept of composition-filters.