We've covered quite a bit in this chapter. We discussed the typical architecture for Push Notifications and gateways, and we covered how to set up Push Notifications, using Boxcar, Apple, and Google Cloud Messaging. We also wrote code to send and receive Push Notifications.

In the next chapter, we will put everything together from the last several chapters to create one proper application that your users might actually want to use. We'll cover various presentation techniques (charts, templates, and so on) and frameworks, as well as how to wire everything together (models, view controllers, routes, and so on).