[ Thanks to jmalasko for this link.
]
“So far, our application, aggroGator, allows a user to
mash up several popular Web services and create an aggregate feed
of those services. Now, to make things a little more interesting,
we want to allow users to subscribe to other users’ feeds (where
each user’s feed is quite possibly an aggregate of feeds itself.)
For example, let’s say we want to set up an account to subscribe to
ourself on Twitter, last.fm, and del.icio.us, so friends can then
subscribe to our aggroGator feed to see all of the activity on
those services. To handle this, we need to once again revisit our
data model.”