source element in RSS 2.0 is the most under-utilized item element yet it solves many of the issues of tracking threads and citing an item’s source. I would like to lift the veil on this optional sub-element of
item and introduce new ways to track related content inside a feed aggregator.
The purpose of the source element according to the RSS 2.0 specification is to “propagate credit for links, to publicize the sources of news items.” It contains two pieces of information about a cited source: a RSS feed URL and the name of the channel.
<source url=”http://www.niallkennedy.com/blog/index.xml”>Niall Kennedy’s Weblog</source>
Using the code above a weblog post could define the source of the data contained within the post. Using the example from Brent Simmons’ post, two posts from separate weblogs discussing the release of a software upgrade could both point at the software vendor’s release page within their source element to give credit and provide a service to their users to track common threads.
A feed aggregator could gather all of the source elements and determine similar sources and near-neighbor relations. A user could browse a commentary by topic, follow a conversation thread, and discover the most commonly cited post within a given topic.
Sources are commonly cited in HTML by including text such as “(via linked source).” A weblog authoring tool could generate a RSS source element when it parses the post and discovers one representation of a source citation. Aggregators supporting authorship tie-ins should pass this data to the weblog authoring tool. If everyone utilizes the specification to its fullest we should have a much richer experience authoring and consuming new content.