Feed

what?

format for delivering regularly changing content

uses

news (most popular) - cnn.comlatest photos from friend - flickr.comlatest change to wiki - wikipedia.comlatest changes to code - subversionlatest bugs - teamtracklatest weather - weather.comAnything which needs to publish latest items that can be broken into discrete items

how does it work

Website publishes a link for its FeedUser subscribes to it, by adding the link to his Feed ReaderThe Feed reader requests the latest items from the FeedIt displays the items which the user hasn't read yetIt refreshes the feed at fixed interval

technicalities

The link for the feed published is just a normal URLThe reader requests the for the latest changes by sending a GET request to the URLThe response is in XML which can be of one of the two formats RSS/AtomThe entire transaction is done using HTTPRSS Spec - http://cyber.law.harvard.edu/rss/rss.htmlAtom RFC - http://tools.ietf.org/html/rfc4287

XML Format

< Feed Details> <title> <description> <last update> <link></Feed Details><Item> <title> <description> <last update> <link></Item><item>....</item><item>....</item>

rss problems

Large number of automated requestsMassive bandwidth usage

Solutions:

Cachingincomplete feedsreduce frequency of requests by clients