// LiveDataHeartbeat
@Override
public Collection<LiveDataSpecification> heartbeat(final Collection<LiveDataSpecification> activeSubscriptions) {
Heartbeat heartbeat = new Heartbeat(activeSubscriptions);
FudgeMsg heartbeatMsg = heartbeat.toFudgeMsg(new FudgeSerializer(getMessageSender().getFudgeContext()));
getMessageSender().send(heartbeatMsg);
return null;
}
}