In the Real WorldWhy Learn XML?

In the Real World Why Learn XML?

It's unlikely to be evident to casual or even power users of Access 2003 how the new XML features will make their life easier or more productive. This is especially true for users who don't intend to export data or move their Access front ends to an intranet or the Internet. If you fall in that category, this and the remaining chapters of Part VI, "Publishing Data to Intranets and the Internet," might not pique your interest.

If your current or intended career involves databases, however, a full understanding of the roles of XML, XSD, XSLT, and XPath will prove to be a critical skill. The amount of Web content delivered from databases will continue to increase in future, so HTML authors and Web page designers need to be conversant with if not proficient in XML and its derivatives. Document-literal XML Web services are XML documents that rely on an embedded schema to describe their payload. Thus, creating and consuming XML Web services requires XML and XSD skills.

Becoming proficient in data-related XML (often called XML Infosets) and, especially, XSLT coding is more challenging than becoming a journeyman VBScript, ECMAScript, VBA, or Visual Basic .NET programmer. Expect a learning curve similar to that for Java or Microsoft's C# language, but not as steep as that for C++. Books are a good starting point, but there's no substitute for working with the complex, real-world data and schemas that many XML texts avoid. Access 2003 is a great source of simple to moderately complex XML documents for gaining an understanding of XML schema language and XSLT coding.

An efficient and satisfying method for learning real-world XSLT is to start with the .xsl presentation files that RPT2HTML4.xsl generates for exported tables and queries. Once you've mastered modifying these relatively simple files, try rolling your own .xsl files to turn attribute-centric SQL Server template queries into formatted HTML tables. (The xml-sql namespace expects attribute-centric XML data.) If you're script-enabled, try adopting ReportML's approach to customizing the formatting of HTML data including adding <A href=http://www...>...</A> tags to open pages having other tables that contain related data. Script is a great way to overcome XSLT's lack of variables with values you can change during the transformation process. (XSLT variables are better described as constants.)

The greatest obstacle to the learning-by-writing process is the lack of production-grade debugging tools for XSLT, especially XSLT code that executes scripted functions. Opening .xsl files in IE 6+ only confirms that the XSLT is well formed. Here's hoping that Microsoft or another enterprising software vendor comes up with a combination authoring-debugging tool that's more effective than today's XSLT editors.