The spec for ActivationSystem.activeGroup seems to require that it throw ActivationException if a previous activeGroup call has been received for the same group. If the activeGroup call appears to succeed from rmid's perspective, but fail (reply is lost) from the group's perspective, the spec prevents the group from making another activeGroup call with the same arguments. This seems to work against reliability. It seems like it should be acceptable to call activeGroup more than once as long as the instantiator and incarnation are the same.