I read a lot of RSS feeds to keep myself up to date. Perhaps too many, almost two hundred articles appear in my Google Reader each day. One of the most busy ones is the DZone front page feed. Not all of it is interesting, so some filtering would be useful.

My first idea was to subscribe to the individual tag feeds ("java", "opinion" etc.) but that leads to duplicates and false positives: An article may be tagged with multiple tags, so when subscribing to "opinion" for example, you'd also get opinions on .NET stuff. Not exactly what I had in mind.

The solution is simple: Download the feed, weed out articles I'm not interested in (ie. blacklist everything tagged with ".net" or "php") and subscribe to the filtered feed. Pretty simple to do with a few lines of code, but you need your own server.

That's where Yahoo! Pipes comes to the rescue. Yahoo! Pipes is an comfortable mashup tool loosely modeled after Unix pipes. It comes with a nice graphical online editor and is pretty easy to use. Within minutes, I created a simple pipe that reads the DZone front page feed and filters entries based on category. In Google Reader, I subscribed to my pipe's RSS output instead of the original front page feed. That's it.