Using RSS News Feeds

Abstract

The Rich Site Summary (RSS) format, previously known as the RDF Site Summary, has quietly become the dominant format for distributing news headlines on the Web.

In this Mother of Perl tutorial, we will write a short Perl script (less than 100 lines) that retrieves an XML RSS file from the Web or local file system and converts it to HTML. Using a Server Side Include (SSI) or similar method, you can easily add news headlines from any number of sources to your Web site.

History

Where did RSS come from you ask? Netscape invented the RSS format for "channels" on Netscape Netcenter (http://my.netscape.com). It was released to the public in March of 1999. The first non-Netscape Web site to incorporate the new format was Scripting News, a popular technology news site run by Dave Winer, president of Userland Software (think Frontier). Interestingly enough, Scripting News had been using its own XML format, scriptingNews, since December of 1997.

In May of 1999, Dave Winer released a new version of the scriptingNews XML format, which added new content-rich elements. Netscape followed suit by adopting most of the new scriptingNews elements into RSS 0.91, which was released in July of 1999.

Userland Software also rolled out their own flavor of my.netscape.com. If you haven't already guessed, it's available at http://my.userland.com.

As far as I know, RSS is the most widely used XML format on the Web today. RSS headlines are available for many popular news sites like Slashdot, Forbes, and CNET News.com, and the list is growing daily.

In a time when "stickiness" is a good, displaying news headlines on your Web site can really help give it the extra "umph" that will encourage users to return. After all, users can only read your president's bio but so many times.

Required Modules

For rss2html.pl to work on your system, you should have a recent version of Perl installed, 5.003 or better. 5.005 is recommended. You will also need the XML::Parser and XML::RSS modules installed.

To install the modules on a *nix system, type:
perl -MCPAN -e "install XML::Parser"
perl -MCPAN -e "install XML::RSS"

If you're using a win32 machine (Win95/98/NT), you have a recent installation of Activestate Perl. If you don't have a recent version, visit http://www.activestate.com.

To install XML::Parser on a win32 machine type:
ppm install XML-Parser

To install XML::RSS on a win32 machine (you must have a C compiler and nmake):

• Download the module from: http://search.cpan.org/dist/XML-RSS/
• Uncompress the zip file and cd to the XML-RSS-0.5 directory
• type: perl Makefile.PL
• type: nmake
• type: nmake install

Next, we'll examine the RSS format in more detail.

rss2html.pl Get the source This script converts an RSS file on the Web or local file system to HTML.