System.Web.SessionState (system.web.dll)interface

This interface should be implemented by a custom HttpHandler (any class that interprets web requests and implements System.Web.IHttpHandler). The IReadOnlySessionState interface contains no members and is used only as a marker. When present, it tells ASP.NET that the HttpHandler should be given readonly access to the HttpSessionState collection.

Every HttpHandler should implement either IReadOnlySessionState or IRequiresSessionState, or session state variables will not be accessible.

public interface IReadOnlySessionState : IRequiresSessionState {
// No public or protected members

    Part I: Introduction to ASP.NET
    Part III: Namespace Reference
    Chapter 40. The System.Web.UI.MobileControls Namespace
    Chapter 42. The System.Web.UI.WebControls Namespace