XML-Enabled Databases
The latest releases of most popular RDBMS systems include some form of direct XML support. Microsoft's SQL Server 2000 includes features such as the OpenXML() function and the FOR XML extension to the SELECT statement. These two features allow XML data to be incorporated into relational queries in addition to returning query results in XML format. Oracle's 8i and 9i products provide comparable functionality.
Retrieving query results from the database server directly in XML format is the most efficient way to integrate XML into an application. Figure 9.4 illustrates how an application can take advantage of an XML-aware database server.
Figure 9.4. Application using XML-aware database and drivers.
Currently there is a lack of standardization by database manufacturers when it comes to exposing XML interfaces. This means that applications written to take advantage of a particular database system will be difficult to migrate to other platforms.