Content Syndication with RSS

Chapter 5. Richer Metadata and RDF

Every public action which is not customary, either is wrong, or, if it is right, is a dangerous precedent. It follows that nothing should ever be done for the first time.

—Francis M. Cornford

The feeds we’ve seen so far are very simple. They provide little information beyond what is needed for the instant gratification of displaying the feed in a human-readable form. Of course, this isn’t such a bad deal — many people only want to display the feeds as they come.

Others, however, are more ambitious in their plans for the RSS feeds they use, and for this they require a far richer set of metadata. In this chapter, we look at metadata and give a basic overview of the Resource Descriptive Framework (RDF). This will prepare us for Chapter 6 and the pleasures of RSS 1.0 — the RDF-based RSS standard.

Metadata in RSS 0.9x

As all good tutorials on the subject will tell you, metadata is data about data. In the case of RSS 0.92, this includes the name of the author of the feed, the date the channel was last updated, and so on. In Example 5-1, the bold code is the metadata. You could remove this data, and the feed itself would still both parse and be useful to the reader when displayed as HTML. The metadata is in the background, silent, but meaningful to those who can see it.

Example 5-1. The metadata within an RSS 0.92 feed

<rss version="0.92"> <channel> <title>RSS0.92 Example</title> <link>http://www.oreilly.com/example/index.html</link> <description>This is ...