Transaction model vs Virtual Synchrony model: bridging the gap

Two important models for building fault-tolerant applications have been independently proposed in the literature, the {\em transaction} model (developed within the context of database applications) and the {\em virtual synchrony} model (proposed initially by the Isis system to handle replication). For a better understanding of the relations between these models, we address the following question: are the basic mechanisms needed to implement both models exactly the same? The paper answers this question by defining the Dynamic-Terminating-Multicast problem, and showing that it can be seen as a generic problem, closely related to the implementation of both the transaction model and the virtual synchrony model. It is thus possible to build a system offering, in an integrated way, both the transaction model and the virtual synchrony model. Such a system could offer powerful primitives that are currently cumbersome or impossible to express in the existing systems.