public void RemoveObserver <Odata>(string topicName, CallBackObserver callbackObserver)
{
HashSet <CallBackObserver> listObserver = CreateListObserverForTopic(topicName);
listObserver.Remove(callbackObserver);
}
// Use this for initialization
public void AddObserver(string topicName, CallBackObserver callbackObserver)
{
HashSet <CallBackObserver> listObserver = CreateListObserverForTopic(topicName);
listObserver.Add(callbackObserver);
}