Total Order (TO) broadcast is a widely used communication abstraction that has been deeply investigated during the last decade. As such, the amount of relevant works may leave practitioners wondering how to select the TO implementation that best fits the requirements of their applications. Different implementations are indeed available, each providing distinct safety guarantees and performance. These aspects must be considered together in order to build a correct and sufficiently performing

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... ication. To this end, this paper analyzes six TO implementations embedded in three freely-distributed group communication systems, namely Ensemble, Spread and JavaGroups. Implementations are first classified according to the enforced specifications, which is given using a framework for specification tailored to total order communications. Then, implementations are compared under the performance viewpoint in a simple yet meaningful deployment scenario. In our opinion, this structured information should assist practitioners (i) in deeply understanding the ways in which implementations may differ (specifications, performance) and (ii) in quickly relating a set of total order algorithms to their specifications, implementations and performance.