SharePoint Development Platform Stack

Figure 1 shows how SharePoint Foundation is built on Microsoft .NET Framework 3.5, ASP.NET, and Internet Information Services (IIS). SharePoint is also built on SQL Server, but you can install SQL Server on a dedicated server that does not have SharePoint installed, which is typical in a production farm. All of these platforms must be running on a 64-bit installation of Windows Server 2008 on the server computers. SharePoint Server, in turn, is built on SharePoint Foundation. There are two editions of SharePoint Server: Standard and Enterprise.

Figure 1. The platform stack for SharePoint development

Perhaps the most noteworthy aspect of the figure is that IIS and ASP.NET are shown as a single platform. This is because SharePoint requires that IIS operate in integrated mode with ASP.NET. Hence, from a SharePoint point of view, they are effectively a single web-hosting application. For more information about this, see the next section, SharePoint as an ASP.NET-IIS Application.
In Figure 1, the smaller boxes that have no fill represent some selected subparts of the platform that contains them, or on which they depend. The two thin, downward-pointing arrows indicate some specific dependencies that are shown only as examples. Many other specific dependencies are not shown in the figure. The thick, left-pointing arrows indicate that the entity on the right side accesses the entity to which the arrow points. For example, BCS accesses external databases.