In this chapter, we learned the basics of publish/subscribe in XMPP. While the premise of pubsub may be rather simple conceptually, it's a very powerful tool upon which many systems covering a huge range of functionality can be built, from social networks to fully federated database systems.

Once we learned about the basics, we went on to take a simple static website and add real-time data to it (well, in the form of made up stock values). To achieve this, we built a publishing client that generated data for us (imagine we were pulling data from RSS feeds, Twitter, or other constantly updating systems!) and published it to a pubsub node.

Once the publisher was completed in a small number of lines of JavaScript, we built a browser-based client that retrieved old data, wrote it to a graph, and then started receiving real-time updates from the server as data was being published.

There are several standard features of XMPP related to pubsub that we did not cover in this chapter. As always...