If this function has been called the same number of times that 'topic' was created by ProviderSession.CreateTopics, then 'topic' is deleted: a 'TopicDeleted' message is delivered, preceded by 'TopicUnsubscribed' and 'TopicDeactivated' if 'topic' was subscribed. (See "Topic Life Cycle", above, for additional details.) The behavior of this function is undefined if 'topic' has already been deleted the same number of times that it has been created. Further, the behavior is undefined if a provider attempts to publish a message on a deleted topic.