Sebastopol, CA--Are today's weblogs similar in influence to radio in the 1930s and TV in the 1950s? The number of blogs has grown in the past two years from 100,000 to 4.8 million, according to "BusinessWeek," and last year's political season saw a wave of grassroots journalists rise to challenge traditional media outlets. "Time Magazine" actually named a "Blog of the Year" for 2004. What's really significant about the now-common blog phenomenon--beyond the personal web sites themselves--is the prevalence of RSS content feeds, the vehicle responsible for the spread of all this new opinion and information.
"Content-syndication technologies are among the Internet's fastest growing," acknowledges Ben Hammersley, author of Developing Feeds with RSS and Atom (O'Reilly US $39.95). "They're for web developers and web site authors--everyone from webloggers and amateur journalists to those running large-budget sites--who want to share their site with others by offering feeds of their content. They're also for developers and news junkies who want to use and share the content other people are syndicating."
A content syndication feed is an XML-based file that allows a web site to share its latest content with other applications. The feeds can be anything from headlines and links to stories to quick summaries or the entire content of a site stripped of its layout. Many sites include a white-on-orange "RSS" or "XML" button, which indicates that it offers a content feed. "Feeds have started to be used as content in their own right," Hammersley adds. "People are building services that only output to a feed and don't actually have a 'real' site at all."
It's easy to see why many webloggers want to supply a feed. But why would commercial web sites want to give away their content? In Developing Feeds with RSS and Atom, Hammersley lists nine reasons, such as increasing traffic to the site, building brand awareness, and raising the site's search engine rankings. Plus, he says, "It gives them a good excuse to play with some cool stuff."
Two years ago, Hammersley's book, Content Syndication with RSS was the first to cover content syndication and its enabling technologies. In Developing Feeds with RSS and Atom, Hammersley shows how this fast-moving field has evolved, and how experienced web developers, tech-savvy webloggers, and application developers can use RSS and its rival technology, Atom, to create content feeds or build services (such as desktop readers) to use them. Considering the confusing and sometimes conflicting documentation about these technologies on the Web, the book is a unique and valuable resource.
"The technology is not all that hard to understand," Hammersley says. "I try to explain where these things came from and why there is so much diversity in what seems on the surface to be a relatively simple field." With wry humor, in the book's introduction he writes, "the standards were not born fresh and innocent, of a streamlined process overseen by the Wise and Good. Rather, they have been dragged into the world and tempered through brawls, knife fights, and the occasional riot."
Indeed, RSS 1.0 and RSS 2.0 are two different specifications created by rival groups with conflicting intentions. After all the infighting, a third group developed a new specification from scratch, which became Atom 0.5. "The three strands each have their own advantages and disadvantages, and their own specific uses," Hammersley explains. His book covers all three in detail.
While early chapters show readers how to obtain or create feeds with available tools that require no programming, the meat of the book focuses on the three specifications and issues that developers need to address when building and consuming feeds. The book explores and explains metadata interpretation, different forms of syndication--such as publish-and-subscribe calls--and the role of web services.
Hammersley includes a generous amount of code, written mostly in Perl, but "the examples are commented sufficiently to make things clear and easily portable," he says. An appendix provides a quick tutorial to XML that should give readers the foundation they need to work with feeds. The book assumes some familiarity with HTML.
"Users of any language will get a lot from this book," Hammersley remarks. "The explanations of the standards and the uses of RSS and Atom are language agnostic. They'll understand the specifications and learn how to use them to their limits."
Developing Feeds with RSS and Atom
ISBN: 0-596-00881-3, 253 pages, $39.95 US, $55.95 CA
O'Reilly Media spreads the knowledge of innovators through its books, online services, magazines, and conferences. Since 1978, O'Reilly Media has been a chronicler and catalyst of cutting-edge development, homing in on the technology trends that really matter and spurring their adoption by amplifying "faint signals" from the alpha geeks who are creating the future. An active participant in the technology community, the company has a long history of advocacy, meme-making, and evangelism.
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