In Chapter 2, we saw how data can be retrieved from Microsoft SQL Server as XML fragments. However, to build client applications or business components that retrieve XML data from SQL Server, we need a way to connect to the database server, submit FOR XML queries, and return the results.
Most Windows platform developers are familiar with the Microsoft ActiveX Data Objects (ADO) data access application programming interface (API). ADO is a COM-based library of components that can be used to access any kind of data in any kind of data source. It's built on top of the OLE-DB API, a standard interface for connecting to and interacting with data sources. ADO version 2.6 ships with SQL Server 2000.
One of the frustrating parts of writing technical content is that the industry never seems to stand still. As I write this chapter, Microsoft is working on ADO.NET, a new, more XML-based data access API for the .NET platform. ADO.NET will introduce many new objects to enable more flexible data solutions. Even so, the functionality of ADO 2.6 will still be available in ADO.NET.