Friday, December 18, 2009

Filter your RSS feeds and getting into troubles?

Do you also have subtle problems when performing simple filter operations on RSS feeds? If yes, well, there's still some hope. Almost since the beginning I experience very strange problems when filtering the RSS feed of my blog for certain categories. I know this should not be problem but unfortunately, it is...

My first address for RSS filtering was Yahoo Pipes! which allows one more than doing simple RSS filtering, it basically allows one to "re-wire the Web". For some reason, if I filter for blog posts associated to a certain category (e.g., computingnow) I always get zero items as shown in the figure below. Very strange as it works for other feeds but not this one. Changing the feed and/or blogging platform is not an option at the moment.

After doing the whole troubleshooting for while, it was clear that I have to search for another solution. That's why I did a Web search to find some alternatives and I found an interesting article describing six ways to filter RSS and there are even more. I tried some (e.g., Feed Rinse just produced an error when filtering for this term and FilterMyRSS works but is currently unavailable) and after some time - quite some time acutally - I wrote the following:

It's a very simple XSLT style sheet that filters for the category 'computingnow'. Next to that I've enabled a cronjob in the home directory of my Web space that executes the following script on a regular basis (e.g., every half an hour or so):
java -jar saxon9.jar -s: -xsl:rss-filter.xslt -o:public_html/ct4computingnow.xml
Well, and that's the story how this article is brought to you and the feed I've filtered myself now is available here. Of course, I could make the XSLT style sheet much more flexible by adding parameter support but that's another story...
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