We're using eventuate[0], which is an event-sourcing framework with deep support for cooperation via shared logs. It's based on the actor framework akka; akka itself has akka-persistence[1], which is similar but different[2]. All of these techs are usable right now.
Though it doesn't feature either implementation (he does something similar on top of Samza), I like this article[3] on the topic: turning the database inside out really is what we're doing.
We have built an implementation of CORFU [1] (the protocol Tango is based on) that runs on Ceph/RADOS, called ZLog [0]. We have a very simple prototype of Tango running ZLog. ZLog could run on other storage systems like Kafka but we have only focused on Ceph/RADOS as the underlying storage.
