XML Developer Tip
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Investigating Rich Site Summary (RSS)
Part of the way I make my living is by writing books about XML, and various XML-based markup languages, sometimes known as "XML vocabularies" or "XML applications." I'm working with recent XML tip collaborator Lucinda Dykes (who helped me translate my piece on referencing the euro symbol in XML documents based on DTD changes into something equivalent based on XML Schema) to design a hands-on project-oriented book on XML right now. In outlining its coverage, we faced an interesting problem: "Which XML applications best illustrates creating XML markup for regular, everyday use on Web sites?"
Some of our selections were no-brainers -- such as XSLT for styling and rendering XML-based content, not to mention working with various XML editors (e.g. XMLSpy) and document processors -- but we also wanted to pick something Web professionals could use to enhance the value and accessibility of their Web sites. That's why we decided to cover an XML vocabulary called the Rich Site Summary (RSS, formerly decoded as RDF Site Summary before it became apparent that this markup language couldn't fit entirely within the Resource Description Format, itself another XML vocabulary).
So what's the deal with RSS anyway? Whatis.com does a great job of defining the markup language as follows: "a method of describing news or other Web content that is available for 'feeding' (distribution or syndication) from an online publisher to Web users. RSS is an application of the Extensible Markup Language (XML) that adheres to the World Wide Web Consortium's Resource Description Framework (RDF). Originally developed by Netscape for its browser's Netcenter channels, the RSS specification is now available for anyone to use."
In other words, what RSS does is to permit a Web site to advertise and describe its content in a way that makes it easy for consumers of such content to search for and locate that information. Thus, it's an important ingredient in closing the gap between sources of and consumers of information, and lets the latter know about the former. It's especially useful for volatile content like news, columns, or features that appear on a regular basis. Content developers create an RSS document that describes Web site content and provides a precise pointer to its location, and then register that document with some RSS publisher directory (where users go to search for descriptions). The real benefit of RSS is that it is easy to use for all kinds of things, such as spreading news flashes, announcing Web site updates, publishing event calendars, propagating software updates, showcasing featured content collections, and promoting items for Web-based auctions, and so forth.
Current popular RSS directories include the following:
Also, great general RSS sites and pointers (a directory in itself) reside at directory.google.com/Top/Reference/Libraries/Library_and_Information_Science/Technical_Services/Cataloguing/Metadata/RDF/Applications/RSS/. An RSS reader or client is also required for consumers to access RSS directories. You'll find numerous such tools available, including:
Here again, Google or another search engine will help you locate lots of other alternatives, if you don't like what you find there.
I'd also like to recommend two great resources for RSS information, specifications, and code examples. A quick hop to www.xml.com's search engine to check on "RSS" turns up a whole raft of useful articles, descriptions, and examples (and Ben Hammersley's book Content Syndication with RSS from parent company, O'Reilly & Associates, 2003, ISBN: 0-596-00383-8, List Price: $29.95 is also worth checking into as well). Mark Pilgrim's story "What is RSS?" is a good place to start learning about RSS, because it includes examples of working code but the Hammersley book is more current and uses up-to-date markup in its examples. Likewise, the Cover Pages offer a peachy overview, with pointers to RSS specifications, FAQs, mailing lists, and other useful info.
My prediction is that if you work with a Web site that incorporates dynamic, regularly-updated content, you'll find a lot to like about RSS, and be able to make it useful with minimum muss and fuss. Happy XML adventures.
About the Author
Ed Tittel is a 20-plus year veteran of the computing industry, who's worked as a programmer, manager, systems engineer, instructor, writer, trainer, and consultant. He's also the series editor of Que Certification's Exam Cram 2 and Training Guide series, and writes and teaches regularly on Web markup languages and related topics.
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