Building Oracle XML Applications

Chapter 15. Using XSQL Pages as a Publishing Framework

In Chapter 8, we explored the two cornerstone features of Oracle XSQL Pages:

• Assembling an XML data page using one or more parameterized <xsql:query> elements

• Transforming that data page for delivery using an associated XSLT stylesheet

However, the Oracle XSQL Pages technology provides many additional features that make it a truly extensible framework for assembling, transforming, and delivering XML information of any kind. In this chapter, we’ll get acquainted with its full feature set by studying some simple examples of each feature.

Overview of XSQL Pages Facilities

We’ll begin with an overview of how XSQL page processing works, and proceed to explore all of the facilities available to your XSQL pages.

Understanding XSQL Page Processing

At the heart of the XSQL Servlet and the XSQL command-line processor is the XSQL page processor, an engine that uses the Oracle XML Parser, the Oracle XML SQL Utility, and the Oracle XSLT engine to breathe life into your XSQL page template whenever the page is requested. Figure 15.1 illustrates what happens when your web server receives a request for SomePage.xsql that contains a reference to the stylesheet SomeStyle.xsl.

Figure 15-1. Process flow for an XSQL page with a stylesheet

The XSQL page processor:

1. Receives a request from the XSQL Servlet to process SomePage.xsql

2. Parses SomePage.xsql using ...