Simon Fell > Its just code > incremental feeds

Brad says The Math is Scary and talks about incremental feeds. Seems to me that all the infrastructure is already in place for this, and this should be doable on the server side without any explicit support from the aggregator clients. Most aggregators already send either an etag or a if-modified-since header, surely the server can use this to work out the set of new posts since that time? In most cases this'll require the server code to take control of generating the etag header, but ought to be trivial, especially for the folks already dynamically generating their RSS feeds. update check the comments for a discussion on caching proxies.