A html page have a tree-like xml pattern with html tag as its branch and text as its node. This branch and node could be extracted using XPath. XPath allowing us to select a certain branch or node of an XML and therefore could be used to extract certain information and treat it differently based on its content and the user requirements. Furthermore a web domain like news website usually have a same html code structure for storing the information on its web pages. This same html code structure could be parsed using the same XPath query and retrieve the same content information element. All of the XPath query for selecting various content could be stored on a XPath Configuration File.
The purpose of nutch are for various web source, not all of the web page retrieved from those various source have the same html code structure, thus have to be threated differently using the correct XPath Configuration. The selection of the correct XPath configuration could be done automatically using regex by matching the url of the web page with valid url pattern for that xpath configuration.
This automatic mechanism allow the user of nutch to process various web page and get only certain information that user wants therefore making the index more accurate and its content more flexible.
The component for this idea have been tested on nutch 1.2 for selecting certain elements on various news website for the purpose of document clustering. This includes a Configuration Editor Application build using NetBeans 6.9 Application Framework. though its need a few debugging.