Q:

How to create a Google Reader?

I need to create a web tool like Google Reader for my college project.
I have 2 question about it:
1) How Google Reader track the read and unread posts ?
2) Google Reader save every post in the db or load the feeds at the moment ?

A:

assign a hash to a single feed post (ie. date+url+??? = hash to identify a single post)
loads them on the fly would be my guess, maybe caches a limited number per user.

