Picture this scene: It's 1999 and you have just received your brand new computer, which sports a super-fast 333 MHz processor, a massive 256 MB of RAM, and a copy of the latest operating system, Windows 98. Not only that, but it also has a 33.6 kbps modem. After setting a wallpaper of your favorite mountain range and adjusting the screensaver to have a cool floating 3D effect, you set about connecting yourself to the information superhighway.

Soon, colleagues and friends find out that you have got yourself connected and start inviting you to connect. Jennifer in the office is using ICQ, so you also install ICQ and start chatting. Meanwhile, you've received an e-mail from your friend Marty, who asks you to install AOL Instant Messenger. Not wanting to be left out, you sign up and connect there too. Several weeks later, you've also installed Yahoo! Instant Messenger and MSN Messenger.

Now, each time your modem completes making the bing-bong electronic noises, you instinctively fire up several instant messaging applications to ensure you don't miss any messages from friends, family, and colleagues. Worse still, if you want to have a group chat with Linda and Marvin, that's not possible since both of your friends have decided to use different instant messaging programs. You begin to think to yourself that there has to be a better way.

Enter XMPP, a federated secure set of standards that allow clients and servers to talk to each other in a common language.

In this chapter, we'll cover the following topics: