This application is a little different from our previous applications in terms of the data that we need to store. Before, we've always stored only data that we get from the user. This time, a user is only going to give us a URL—the path to a podcast feed—and we have to get all the data from that. Then, later, we need to check that same source for updates. This requires a lot more work on our part.

You might be thinking about how we're going to get this podcast data. Of course, there are only two places from which we can pull in this data: the client and the server. Both are possible; however, things will go a lot more smoothly if we choose to get this data on the server side. Here's why: to prepare the data on the client side would require us to first get the feed (which is a little more than simple, because it's a cross-domain request); then, we have to parse that to get the podcast and episode data we need, before sending the data back to the server for...