XML Hacks

Use Cocoon to Create a Well-Formed View of a Web Page, Then Scrape It for Data

Cocoon is a popular web development framework from Apache.

To an XML hacker, the Web is a frustrating place. Little islands of well-formed XML content are awash in vast seas of “tag soup” in the form of malformed HTML documents [Hack #49] . Using a technique known as screen-scraping, it’s possible to extract information from these pages, relying on knowledge of specific markup practices or document structures to pick out the data items from amongst the presentation elements.

Generally, screen-scraping involves using text processing tools like Perl that ignore the markup completely. However, there are ways to apply screen-scraping techniques using XML tools such as XSLT, the benefit being that one can go a little further with the tools immediately at hand without having to context switch to another environment—good news when you’re after fast results.

This hack will demonstrate how to use elements of Cocoon (http://cocoon.apache.org/), an open source XML processing framework that can create a well-formed view of any web page and then apply XSLT to the results to extract some useful metadata.

Cocoon in 60 Seconds

For the uninitiated, Cocoon is an open source XML processing framework written in Java. It has a loyal community that is continually enhancing its functionality, but at the core is a very simple but powerful design pattern: the pipeline.

A Cocoon pipeline consists of three basic components: a Generator, ...