In my current project I needed to access the Session state in a Generic Handler. To my dismay, i realized that the Session StateBag was null. The StateBag class is sealed and manages the Viewstate of the Asp.net server controls and pages.

Upon discussion with my colleague, Mr. Hamed, we found the solution to my problem. Using the IRequiresSessionState interface in System.Web.SessionState, we got access to Session state.

According to Microsoft “Specifies that the target HTTP handler requires read and write access to session-state values. This is a marker interface and has no methods.“

Another option was to use the IReadOnlySessionState interface (Specifies that the target HTTP handler requires only read access to session-state values. This is a marker interface and has no methods.)

Needless to say, there is a performance increase in the latter case and if your requirement is only to read Session state, then that would be the right choice