find which of a user's tweets were favorited

If I understand correctly Twitter only lets you check which Tw开发者_运维百科eets a user favorited, and not which of his tweets were favorited by other users. (e.g. http://api.twitter.com/1/favorites/aplusk.xml).

Sites like Favstar.fm offer that, I wonder how?

Seems unreasonable to crawl all the users favorites to cross them to favorited of a certain user. (even if you crawl only the friends of that user)

update: Favstar know of new favorited tweets in real time. it seems unlikely they crawl all of your friends to get that.

Ok, i think i figured part of it out:

Favstar have many authenticated users' so they can access their User Stream (http://dev.twitter.com/pages/user_streams)

That way they can get the new favorites, by streaming, and just cross them to the user\tweet it was favorited to, thus can display in real time your new favorited tweets.

The important part here is having many authenticated users, without that this still seems impossible to me. Though, its like the chicken and the egg, how did they convince users to authenticate if they didn't have many users yet(?).

If anyone has a better idea...

Amazing how creativity is a significant part of this CS world. Modern Art

If FavStar has been approved for increased rate limits, it would be pretty trivial for them to crawl your friends and grab a list of Tweets that they have favorited.

Favstar has access to the Twitter data firehose. It is a live stream of every single tweet and user action.

You can get access to part of it using Gnip. See this Twitter forum question about How to Access the Twitter Firehose

To implement a similar set of functionality around Twitter data would cost the developer