In application server systems, such as J2EE, replication is an essential strategy for reliability and efficiency. Many J2EE implementations, both commercial and open-source, provide some replication support. However, the range of possible strategies is wide, and the choice of the best one, depending on the expected application profile, remains an open research question. To support research in this area, we introduce a framework for prototyping J2EE replication algorithms. In effect, it divides replication code into two layers: the framework itself, which is common to all replication algorithms, and a specific replication algorithm, which is "plugged in" to the framework. The division is defined by an API. The framework simplifies development in two ways. First, it keeps much of the complexity of modifying a J2EE implementation within the framework layer, which is implemented only once. Second, through the API, ication algorithm sees a highly abstracted view of the components ...