Scroll down functionality in RSS reader like Google Reader

Question

I have implemented a simple RSS reader in Java. I hit a URL and I get back some XML text. I parse it and retrieve data that I'm interested in. Now I want to implement what Google Reader is doing. It has a functionality by which we can scroll down and see old posts. How can I get these old posts as what I see is every time I hit the URL I get the same XML back?

Answer 1

Google hits the rss links much more often than you read it, and stores all the articles in a database. So when you read it and you scroll down in Google Reader, it actually shows you all the articles it stored in the database. The RSS url is kind of only used by Google Reader to fill its database, but not directly for the display.