ASP.NET can manage session state out-of-process by using a Windows service called the ASP.NET state service. The System.Web.SessionState.StateRuntime class is used by unmanaged code in this service to manage session data. This class supports the .NET Framework infrastructure implementation of the ASP.NET state service and is not intended be used directly from your code.

Using the ASP.NET state service is not the default method of managing sessionstate in ASP.NET; ASP.NET supports in-process session-state management by default. It also supports a second out-of-process option that manages session state in a Microsoft SQL Server database, and it enables custom session-state management solutions. For more information about session-state storage options, see Session State Modes.