by Daniel S. Bricklin
What problem does RSS solve?
Most people are interested in many Web sites whose content changes on an unpredictable schedule. Examples of such Web sites are news sites, community and religious organization information pages, product information pages, medical Web sites, and weblog s. Repeatedly checking each Web site to see if there is any new content can be very tedious.
E-mail notification of changes was an early solution to this problem. Unfortunately, when you receive e-mail notifications from multiple Web sites they are usually disorganized and can get overwhelming, and are often mistaken for spam.
RSS is a better way to be notified of new and changed content. Notifications of changes to multiple Web sites are handled easily, and the results are presented to you well organized and distinct from e-mail.
How does RSS work?
RSS works by having the Web site author maintain a list of notifications on their Web site in a standard way. This list of notifications is called an RSS feed. People who are interested in finding out the latest headlines or changes can check this list. Special computer programs called RSS aggregators have been developed that automatically access the RSS feeds of Web sites you care about on your behalf and organize the results for you. (RSS feeds and aggregators are also sometimes called RSS channels and RSS readers.)
Producing an RSS feed is very simple and hundreds of thousands of Web sites now provide this feature, including major news organizations such as the New York Times, the BBC, and Reuters, as well as many weblogs.
What information does RSS provide?
RSS provides very basic information to do its notification. It is made up of a list of items presented in order from newest to oldest. Each item usually consists of a simple title describing the item along with a more complete description and a link to a Web page with the actual information being described. Sometimes this description is the full information you want to read (such as the content of a weblog post) and sometimes it is just a summary.
For example, the RSS information for headlines on a local news Web site could contain the following information:
Title: Sidewalk contract awarded
Description: The city awarded the sidewalk contract to Smith Associates. This hotly contested deal is worth $1.2 million.
Title: Governor to visit
Description: The governor is scheduled to visit the city on July 1st. This is the first visit since the election two years ago. The mayor is planning a big reception.
The RSS information is placed into a single file on a Web site in a manner similar to normal Web pages. However, the information is coded in the XML computer language for use by a program (the RSS aggregator) and not by a person like a normal Web page.
RSS aggregator programs
Think of an RSS aggregator as just a Web browser for RSS content. RSS aggregators automatically check a series of RSS feeds for new items on an ongoing basis, making it is possible to keep track of changes to multiple Web sites without needing to tediously read and re-read each of the Web sites yourself. They detect the additions and present them all together to you in a compact and useful manner. If the title and description of an item are of interest, the link can be used to quickly bring the related Web page up for reading.
There are many RSS aggregators available. Some are accessed through a browser, some are integrated into email programs, and some run as a standalone application on your personal computer.
How do I find out if a Web site has an RSS feed?
It is getting more and more common for Web sites to have RSS feeds. They usually indicate the existence of the feed on the home page or main news page with a link to RSS, or sometimes by displaying an orange button with the letters "XML" or "RSS." RSS feeds are also often found with a "Syndicate This" link. Text RSS links sometimes (there are lots of variations) point to a Web page explaining the nature of the RSS feeds provided and how to find them. The buttons are often linked directly to the RSS feed file itself.
Once you know the URL of an RSS feed, you can provide that address to an RSS aggregator program and have the aggregator monitor the feed for you. Many RSS aggregators come preconfigured with a list to choose from of RSS feed URLs for popular news Web sites.
How is the RSS feed file produced?
Unless you are maintaining a Web site or want to create your own RSS feed for some other purpose, how the RSS feed is produced should not be of concern and you may skip this section.
The special XML-format file that makes up an RSS feed is usually created in one of a variety of ways.
Most large news Web sites and most weblogs are maintained using special content management programs. Authors add their stories and postings to the Web site by interacting with those programs and then use the program's "publish" facility to create the HTML files that make up the Web site. Those programs often also can update the RSS feed XML file at the same time, adding an item referring to the new story or post, and removing less recent items. Blog creation tools like Blogger, LiveJournal, Movable Type, and Radio automatically create feeds.
Web sites that are produced in a more custom manner, such as with Macromedia Dreamweaver or a simple text editor, usually do not automatically create RSS feeds. Authors of such Web sites either maintain the XML files by hand, just as they do the Web site itself, or use a tool such as Software Garden, Inc.'s ListGarden" program to maintain it. There are also services that periodically read requested Web sites themselves and try to automatically determine changes (this is most reliable for Web sites with a somewhat regular news-like format), or that let you create RSS feed XML files that are hosted by that service provider.
In addition to notifying you about news headlines and changes to Web sites, RSS can be used for many other purposes. There does not even have to be a Web page associated with the items listed -- sometimes all the information you need may be in the titles and descriptions themselves.
Some commonly mentioned uses are:
- Notification of the arrival of new products in a store
- Listing and notifying you of newsletter issues, including email newsletters
- Weather and other alerts of changing conditions
- Notification of additions of new items to a database, or new members to a group
One RSS aggregator is all that you need to read all of the RSS feeds, whether they are headlines, alerts, changes, or other notifications.
This tutorial is reprinted with permission from Software Garden, Inc .