Where are all the topic objects stored? and How can I delete them?
From the [Push to an Existing Site](http://socketo.me/docs/push) tutorial I can see that you had to create an array of topics so that you can access a topic from the `onBlogEntry` function:

```
protected $subscribedTopics = array();
public function onSubscribe(ConnectionInterface $conn, $topic) {
    if (!array_key_exists($topic->getId(), $this->subscribedTopics)) {
        $this->subscribedTopics[$topic->getId()] = $topic;
    }
}
public function onBlogEntry($entry) {      
    ....
    $topic = $this->subscribedTopics[$entryData['cat']];
    $topic->broadcast($entryData);
}
```

However, what if I want to delete a topic? I can deduce that the topic object are created automatically somewhere whenever a client subscribes to it and are stored somewhere and new connections are added to them whenever someone subscribes to it. 

So my questions:
1) When does a topic object get created?
2) Where are all the topic objects stored?
3) How can I access them through my application class? I see no methods in `WampServerInterface` that let me access the list of topics?
4) How can I _properly_ delete a certain topic entirely?
5) Does a topic object get automatically deleted after a certain period of time?
6) How do I prevent a client from creating a topic without blocking them by ip?

Sorry for the too many question, but they are all related to each other. :+1: 
