An Introduction to XML

If you've ever resorted to hair pulling because you couldn't get the data you needed in a format that Access could understand, Extensible Markup Language (XML) might be for you. Technical gurus define XML as a platform-independent markup language for structured documents. That definition might not mean much to you, and because this is a chapter on automating the entire process anyway, we won't discuss XML basics at great length. All you really need to know is that XML is a technology that makes sharing data easy, regardless of the data's original format. If the application can export the data as an XML file, Access can import it. XML takes the hair pulling out of data-sharing tasks.

Although XML has been around for a while, Access only began to support it in version 2002. Access 2003 supports the following XML file types:

• XML A formatting standard for structured files. An XML file uses tags to organize the actual data into data blocks.

• XSL A standard for modifying imported or exported data. Use an XSL file to format the data in the XML file. Often, these two files are combined by embedding the XSL data into the XML file.

• XSD A standard that defines or describes a database structure in XML terms. These schema definition files contain data type and constraint information about the tags and data in a corresponding XML file.

In the course of this chapter, you learn how to work with all three of these file types. You'll see how XML can be used to carry data, how XSL is used to add formatting, and how XSD is used to capture information about the structure of data.

NOTE

A structured file is a type of text file that uses what's known as tags to identify the data and metadata. For instance, an XML file that contains customer data might contain the tags <CustomerName>, <CustomerAddress>, and so on. Access can interpret these tags as column headings. Most likely, the actual data for these columns would follow the corresponding tag.

In addition, the features of Access XML can create a Web-ready HTML document. You learn more about that later in this chapter ("Exporting a Web-Ready File").