Remember bot@localhost? Fire up Empathy and log in with the JID bot@localhost and password tellnoone. As Marty and Jennifer are passing the ball to each other, bot@localhost could send the hello message to either player an hijack a place in the game! While this might be interesting, this is not the kind of behavior we would hope to see in a more advanced application that uses XMPP. Instead, we would want to make sure someone like bot can't inject themselves into the game (I'll bet you could make bot change one of the player's paddle positions). We wouldn't want game control messages and chat messages to be shown in the same chat window although one thing we could do is enable chat in XMPPong 

In the following chapter, we are going to address these issues. We will look into employing custom namespaces, creating a server-side component that can help prevent cheating. We will even keep track of wins and losses and create a leaderboard of the best players. For...