A Transparent Light-Weight Group Service

Virtual synchrony, also known as view synchrony, has proven to be a powerful paradigm to build distributed applications. Informally, virtual synchrony provides to each process group membership information in the form of {\em views} and guarantees that all processes that install a given view have delivered the same set of messages from the previous view. Implementations of virtual synchrony usually require the use of failure detectors and failure recovery protocols. There is a range of applications that require the use of a large number of groups with the same membership. In such applications, significant performance gains can be attained if these groups share the resources required to provide virtual synchrony. A service that maps user groups into instances of a virtually synchronous implementation is called a Light-Weight Group Service. This paper proposes a new design for the Light-Weight Group Service protocols that circumvents some of the limitations of previous approaches. As a test case, the new protocols were implemented in the Horus system, although the underlying principles can be applied to other architectures as well. The paper also presents performance results from this implementation