Building on my previous article about Blog Technologies, the next web 2.0 technology to introduce is a web feed. A web feed is a data format used for providing readers with frequently updated content. Let's say, for example, we wanted to add a new feature to the Newton PTO Council website which collected news and announcements from all 21 Newton school PTOs so that parents had one place where they could read it. Web feeds would serve two important functions.
- Each school PTOs to make their news & announcements available as web feeds which could then be aggregated into one central News & Announcements page for parents to filter and read.
- Parents (and others, of course) could also use a feed reader, such as Google Reader or RSSOwl, to subscribe those feeds into their own personal collection of web feeds, which could also include feeds from all over the web
In this example, PTOs act as content producers who syndicate their news and announcements through web feeds, which would allow the Newton PTO Council to act as a News & Announcements aggregator and parents/others to be subscribers. The content delivered by a web feed is typically HTML-formatted text (webpage content) or links to other webpages, but can also contain audio and video clips.
Web pages that are available as a web feed are usually marked with the web feed icon (orange square on left). The two key technologies that make web feeds possible are standard XLM formats, known as RSS and Atom.
RSS is most commonly known as "Really Simple Syndication", but officially stands for "RDF Site Summary". There's a long and sordid history to RSS that includes many incompatible versions and arguments about which is the official one, but suffice it to say there are two major versions: RDF (RSS v1.x) and RSS v2.x.
Atom is another format for web feeds which was motivated by the RSS controversies and shortcomings. The Atom syndication format was published as an IETF in RFC 5023.
In my next article, I'll discuss web feed aggregators and readers.
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