Syndicate Your Site

asp:feature

LANGUAGES: C#

ASP.NET VERSIONS: 1.0 | 1.1 | 2.0

 

Syndicate Your Site

Dynamically Create RSS Syndication Feeds

 

By Scott Mitchell

 

If you visit many weblogs, such as those at http://blogs.msdn.com or http://weblogs.asp.net, you may have noticed that many blogs contain a little orange button with the text XML or RSS (see Figure 1). Clicking on that button takes you to a page that dumps out a bunch of XML content. This XML content, called an RSS syndication feed, contains information about the blog's latest posts, such as the title of a post, when it was made, a link to the complete post, and a synopsis of the post. RSS is a standard that specifies an XML format for syndicating metadata about Web site content in a machine-readable format.

 

Figure 1: Sites that provide an RSS feed typically use a little orange button that links to the site's RSS feed.

 

Syndicating content through RSS isn't limited to blogs; a bevy of Web sites syndicate information about their content using RSS, including CNet's News.com, Yahoo! News, eWeek.com, and Microsoft's MSDN site. You may be wondering why any Web site would want to syndicate metadata about its content. There are two main reasons:

 

One. Other Web sites can read the syndicated information, and display this on their own Web site. This gives the syndicated content more exposure since it can be easily delivered to multiple Web sites.

 

For example, at the official ASP.NET Web site (http://www.asp.net), there's an RSS feed listing the latest ASP.NET-related articles on the Web. On the Web site I run, 4GuysFromRolla.com, I list these recent articles on the homepage (http://aspnet.4GuysFromRolla.com), so a visitor to my site can see the titles and descriptions of the latest ASP.NET articles gathered by http://www.asp.net. Clicking on one of these titles will take the user to the particular article.

 

Two. Many people are starting to use RSS aggregators as a means for keeping up-to-date with online information. An RSS aggregator is a desktop or Web application that periodically checks the RSS feeds from a specified list of sites. If there are any new content items, the RSS aggregator alerts the user so that they can view information about the new content through their aggregator program, without having to fire up a browser and visit the site. Web sites that want to attract those who are using RSS aggregators need to provide information about their latest content using RSS.

 

In Displaying Syndicated Content, which examined how to consume an RSS feed and display it in an ASP.NET Web page. In this article, we'll look at how to syndicate content using RSS. The lessons learned and code presented in this article will be especially beneficial to those who maintain a Web site that provides regularly updated content and who are interested in extending their content's reach through syndication.

 

The History of RSS

By 1999, Netscape was creating its my.netscape.com Web site, which, like My Yahoo! and other personalized portal sites, allowed users to customize the information displayed on the personalized portal's home page. Netscape needed a standardized way to consume and display different content on a user's personalized homepage. To surmount this problem, they introduced a standardized way by which a Web site could syndicate information about its content. This standard was called RDF Site Summary (RSS) 0.9, as it required conformance to a previous W3C standard called RDF. (RDF is a standard for providing information in a machine-readable, XML format. See http://www.w3.org/RDF/ for more information.) Eventually RSS 0.9 became RSS 1.0.

 

As the RSS 1.0 specification was being formed, Netscape introduced RSS 0.91, which dropped the adherence to the RDF specification. Dave Winer then independently extended RSS 0.91 to RSS 0.92, adding functionality to the RSS spec. The latest work on RSS done by Dave Winer is RSS 2.0. With this latest version, Dave has changed the meaning of the RSS acronym from RDF Site Summary to Really Simple Syndication.

 

The important thing to understand is that there is a bit of a difference between the various RSS versions, most noticeably between RSS 1.0 (which maintains adherence to the RDF standard), and RSS 0.91, RSS 0.92, and RSS 2.0 (which does not). When deciding to syndicate your Web site's content, you'll need to choose which standard to use to syndicate your site's content. There's really no wrong choice; virtually all RSS aggregator applications can consume both valid feeds from any RSS version. However, I would encourage you to use the latest version, RSS 2.0, as it is the standard version we'll be syndicating for in this article. Therefore, from this point forward, when I use the term RSS I am referring to RSS 2.0.

 

Know the RSS 2.0 Specification

RSS is designed to syndicate information about Web site content. For example, the Web site I maintain, 4GuysFromRolla.com, offers an RSS feed (http://aspnet.4GuysFromRolla.com/rss/rss.aspx) that provides the following information about the 10 most recent articles:

• The title of the article.
• The URL of the article.
• The date and time the article was published.
• A short synopsis of the article.

 

The RSS specification provides pre-defined XML elements to express this and other information about a Web site's content items. Additionally, RSS provides XML elements to furnish information about the syndication channel. In RSS, a channel provides specific syndicated content. Each RSS feed contains a single channel. A Web site can contain an arbitrary number of RSS feeds, and can therefore contain an arbitrary number of channels. A Web site might opt to use multiple RSS feeds, having each feed focus on a specific type of content. Yahoo! News, for example, provides 16 separate RSS feeds at http://news.yahoo.com/rss - one for top stories, one for U.S. news, one for world news, one for business news, and so on. RSS channels are akin to television channels in that each TV channel provides a specific type of content, e.g. MTV provides music videos while CNN provides news.

 

The basic form of an RSS 2.0 document contains an element as the document root. The element contains a single child, . In the element are elements providing information about the RSS channel itself, as well as an element for information about each syndicated content item (see Figure 2). The official RSS 2.0 specification is available online at http://blogs.law.harvard.edu/tech/rss.

 

  

    

    http://www.4GuysFromRolla.com/

    The latest headlines from

                         4GuysFromRolla.com

    Copyright 2004 Jupitermedia

              Corporation All Rights Reserved.

    180

    en-US

    [email protected]

    

      

      http://4guysfromrolla.com/020404-1.aspx

      

        This article looks at using HTTP handlers to

        prevent HTTP access to certain types of files.

      

      [email protected]

      Wed, 08 Feb 2004 03:12:00 GMT

    

    

      

      http://4guysfromrolla.com/012804-1.aspx

      

        This article examines skmMenu, an open-source

        custom ASP.NET menu control.

      

      [email protected]

      Wed, 28 Jan 2004 06:51:00 GMT

    

    

      

      http://4guysfromrolla.com/010704-1.aspx

      

        This article, by Jisun Lee, examines how to create

        and consume .NET Web services.

      

      [email protected]

      Wed, 07 Jan 2004 12:09:00 GMT

    

  

Figure 2: An RSS 2.0 syndication feed contains an element for each of the site's recent content items. The elements preceding the elements provide information about the Web site.

 

As Figure 2 illustrates, the RSS feed contains a single element. The is described with elements such as