We did http://ftalphaville.ft.com using Wordpress, and speaking as someone who's actually had to wade through pretty much the whole codebase, let me tell you it seriously sucks.

Their highlights include messing with the raw POST data to limit access, function calls chained eight long and comments like "This probably isn't needed anymore" all over the place.

In this three-part series, I'll show you how to create a chain of responsibility across different classes, which hopefully will give you a better understanding of how this schema can be implemented with PHP.

Since it's just the first part in the esries, they start with the whys and hows of the chain of command process before getting on with the actual code. For the foundation, they create some subclasses that will make the parts of the chain. Next up is combining them and, finally, making the "master class" to combine the links of the chain together. They use a "DataServer" example to work with local files.