RSS Viewer Applet: Window to the World of News (1/4) - exploring XML

RSS Viewer Applet: Window to the World of News

Coming back to this episode's main topic of "News on the Web" we will develop an applet for viewing and navigating RSS channels. Let's put our newfound knowledge from the former article on news formats to good use and create a useful tool for every Web site that intends to publish information in RSS. Every now and then we will come across some best practices of software development from WikiWeb, the site that incubated Extreme Programming.

How do we do it?

We will start by doing the simplest thing that could possibly work, focusing on the RSS parser and neglecting user interface and presentation aspects at first, as well as the "standards way of doing things." We will then incrementally add more bells and whistles as we go.

How do we start then?

First we need to design our little program, which in this case is more like collecting the ingredients for the RSS alphabet soup. We need -

• an XML parser. Aelfred is a good candidate for an applet, being small and fast.
• an RSS parser on top of the XML parser. We will create two classes:
  1. RSSChannel to hold all of the data from the RSS file
  2. RSSHandler to receive the callbacks from Aelfred and feed the information into RSSChannel
  We could combine both into one in order to save a few bytes in the jar file and the Java VM, but it would be less cleanly designed and we want to avoid premature optimization.
• an applet class RSSViewerApplet to use all of the above and create the user interface from the data collected in RSSChannel.

Let' s look at each of them in turn, starting with the Aelfred XML parser.

Produced by Michael Claßen
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URL: https://www.webreference.com/xml/column7/index.html
Created: Feb. 08, 2000
Revised: Feb. 08, 2000