Package tracking has got to be one of the most obvious applications that anyone can think of for RSS. But for some reason, the idea has evaded companies like Federal Express, United Parcel Service, the United States Postal Service, and other logistics companies. Not that the idea hasn't been mentioned before. Earlier this year, I wrote up the idea of personal RSS and how it can be used for lots of high-volume applications like auctions and package tracking. The only question I had was whether an RSS system could scale to support the one-to-one mapping of a dynamic record (one with a changing status field) to an RSS feed. For a company like FedEX that apparently ships more than 5 million packages daily, the number of RSS feeds it would have to run--given that most shipments span two or three days--would be staggering.
Back when I questioned whether a system like that could scale, Sun XML guru Tim Bray chimed in to say that it could. Now, I guess we'll get to see the proof. Only the shippers aren't the ones who will be doing the proving. Instead, it appears as though Bloglines will be doing the heavy lifting. What I've been calling "personal RSS," and Bray has called "private syndication," Bloglines is calling Unique-To-Me Info Updates. But as I learned from Bloglines founder Mark Fletcher, it's not really RSS (though it could be for those who really want it to).
According to Fletcher, each of the different shippers have a variety of APIs so that third parties can access their shipping information. Among the various APIs, one is usually XML-based and it is those XML APIs that Bloglines is taking advantage of. However, Bloglines is not converting the data it mines through those XML APIs into RSS feeds that can be subscribed to with any RSS reader. Said Fletcher, "If you have a tracking number and it becomes a subscription in your Bloglines account, once it's a subscription, we start pinging the service on a regular basis looking for changes in status. If the status changes, you'll see that in our aggregator." You don't have to use Bloglines, though, to keep track of status changes. According to Fletcher, if you use a third-party tool like Feeddemon