Summary

The case study presented in this chapter was of a real family of stylesheets, used for a real application, and not just developed for teaching purposes. It's perhaps slightly atypical in that much of it was written by XML and XSLT experts who developed the languages while they used them. However, it shares with many other projects the fact that the stylesheets were developed over a period of time by different individuals, that they were often working under time pressure, and that they had different coding styles. So, it's probably not that dissimilar from many other stylesheets used in document formatting applications.

The phrase "document formatting" is crucial. The main tasks performed in this stylesheet are applying HTML display styles to different elements, generating hyperlinks , and formatting tables. These are all tasks that lend themselves to using the rule-based design pattern.

I think there are three main messages to come out of this study:

• Within an application that is doing very simple document formatting ninety percent of the time, it is possible to get benefits by using structured data for small parts of the information that have rich semantics-in this case, examples are the markup used for syntax productions , function prototypes , issue tracking, and error listings. The availability of XSLT really does enable you to use XML to represent the semantics of the data, uninfluenced by the way it is to appear on screen.

• Although most of this can be done reasonably easily using XSLT 1.0 facilities, as soon as the data gets complex, XSLT 2.0 features start to make a big impact.

• Within any complex publishing operation that's producing a large suite of documents, the key to success is not so much the detail of how individual stylesheets are coded, but rather the overall structure of how many stylesheet modules there are, how they relate to each other, and how change is controlled.

The case study in the next chapter will be a very different kind of application-one that uses a highly structured data, and displays it in a very different form from the way it arrives in the source document.