The SQL Server 2000 Web Architecture

Three major pieces provide Web access and XML support in SQL Server 2000 databases. The SQL Web component (also known as the ISAPI component) accepts database commands in HTTP requests from Web clients (e.g., browsers) and returns HTTP responses. The Microsoft Data Access Components (MDAC) accept queries in either conventional SQL or the new XPath query language, along with formatting instructions, and return results as XML, HTML, or binary documents. The SQL 2000 database server accepts SQL commands and returns either XML or binary results; the data access components translate commands into SQL for the database server and format the results it returns.

These components can be used separately as well as together, supporting a variety of application architectures other than the one shown here. For example, in an Active Server Pages (ASP) Web application, a set of custom ASPs can take the place of the SQL Web component and invoke the SQL 2000 XML features through MDAC. Similarly, stored procedures running on the database server use SQL Server’s XML extensions directly, without going through MDAC.