Microsoft Internet Information Server (IIS) 4.0 provides a gateway between business services and user services in an n-tier application. IIS extends your applications to the Web, over either a corporate intranet or the Internet. For more information on IIS, see the site http://www.microsoft.com/iis.
IIS can be programmed through the Internet Server Application Programming Interface (ISAPI). Active Server Pages (ASP), the environment that hosts much functionality in the BackOffice Developer's Guide samples, is an example of an ISAPI application. ASP is the language-neutral, interpreted, server-side scripting environment you can use to create and run dynamic interactive Web-server applications. ASP allows you to combine DHTML, scripting, and components.
For more information on developing ISAPI applications, see the Internet Information Services SDK in the "Web Services" section of the Microsoft Platform SDK.
IIS also works closely with Microsoft Transaction Server (MTS) 2.0, which provides a number of services to applications. This conjunction of MTS and IIS, along with the business objects you create and the data access objects you call from them, make up the bulk of the business-services tier in the n-tier programming model of Windows DNA.