When considering web 2.0 paradigm web feeds become an important topic to discuss. Syndication of site content is considered an important Web 2.0 feature, where the users can grab the information from many sources and customize them to retrieve them in a more convenient manner. A web feed or news feed is a data format used for providing users with frequently updated content. RSS which is commonly known as the abbreviation of "Really Simple Syndication" or sometimes "Rich Site Summary" is a family of web feed formats used to publish frequently updated web contents. RSS has many different versions, with two mostly known parallel formats. RSS 1.* and RSS 2.* both are maintained parallel by different organizations and have two unique formats. RSS 1.* (RDF branch) is owned by RSS-DEV Working Group and RSS 2.* is owned by UserLand.
The Atom Syndication Format is an XML language used for web feeds, while the Atom Publishing Protocol (AtomPub or APP) is a simple HTTP-based protocol for creating and updating web resources. Being an XML themselves, web feeds can be parsed to java objects using XMLBeans.
A well known application for creating mashups from the web feeds is Yahoo Pipes. Pipes is a free online service that lets you remix popular feed types and create data mashups using a visual editor.
 A Pipe.
 RSS Tutorial