This five-part article series will introduce you to Web Services. If you've ever wanted to incorporate them into your web sites, this is a good place to start. This article is excerpted from chapter 20 of the book Beginning PHP and Oracle: From Novice to Professional, written by W. Jason Gilmore and Bob Bryla (Apress; ISBN: 1590597702).
Given that the entire concept of Web Services largely sprung out of the notion that XML- and HTTP-driven applications would be harnessed to power the next generation of business-to-business applications, it’s rather ironic that the first widespread implementation of the Web Services technologies happened on the end-user level. RSS solves a number of problems that both Web developers and Web users have faced for years.
All of us can relate to the considerable amount of time consumed by our daily surfing ritual. Most people have a stable of Web sites that they visit on a regular basis, and in some cases, several times daily. For each site, the process is almost identical: visit the URL, weave around a sea of advertisements, navigate to the section of interest, and finally actually read the news story. Repeat this process numerous times, and the next thing you know, a fair amount of time has passed. Furthermore, given the highly tedious process, it’s easy to miss something of interest. In short, leave the process to a human and something is bound to get screwed up.
Developers face an entirely different set of problems. Once upon a time, attracting users to your Web site involved spending enormous amounts of money on prime-time commercials and magazine layouts, and throwing lavish holiday galas. Then the novelty wore off (and the cash disappeared) and those in charge of the Web sites were forced to actually produce something substantial for their site visitors. Furthermore, they had to do so while working with the constraints of bandwidth limitations, the myriad of Web-enabled devices that sprung up, and an increasingly finicky (and time-pressed) user. Enter RSS.
RSS offers a formalized means for encapsulating a Web site’s content within an XML-based structure, known as a feed. It’s based on the premise that most site information shares a similar format, regardless of topic. For example, although sports, weather, and theater are all vastly dissimilar topics, the news items published under each would share a very similar structure, including a title, an author, a publication date, a URL, and a description. A typical RSS feed embodies all such attributes, and often much more, forcing an adherence to a presentation-agnostic format that can in turn be retrieved, parsed, and formatted in any means acceptable to the end user, without actually having to visit the syndicating Web site. With just the feed’s URL, the user can store it, along with others if he likes, into a tool that is capable of retrieving and parsing the feed, allowing the user to do as he pleases with the information. Working in this fashion, you can use RSS feeds to do the following:
Subscribe to any of the numerous Web-based RSS aggregators and view the feeds via a Web browser. Examples of popular online aggregators include Google Reader (http:// www.google.com/reader/), NewsIsFree (http://www.newsisfree.com/), and Bloglines (http://www.bloglines.com/).
Retrieve and republish the syndicated feed as part of a third-party Web application or service. Later in this section, you’ll learn how this is accomplished using the Magpie RSS class library.
Figure 20-1. The RSS Bandit interface
WHO'S PUBLISHING RSS FEEDS?
Believe it or not, RSS has actually officially been around since early 1999, and in previous incarnations since 1996. However, like many emerging technologies, it remained a niche tool of the "techie" community, at least until recently. The emergence and growing popularity of news aggregation sites and tools has prompted an explosion in terms of the creation and publication of RSS feeds around the Web. These days, you can find RSS feeds just about everywhere, including within these prominent organizations:
