MemberUp mUp = (MemberUp) message;
if (mUp.member().hasRole("compute"))
nodes.add(mUp.member().address());
} else if (message instanceof MemberEvent) {
MemberEvent other = (MemberEvent) message;
nodes.remove(other.member().address());
} else if (message instanceof UnreachableMember) {
UnreachableMember unreachable = (UnreachableMember) message;
nodes.remove(unreachable.member().address());