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Links of HttpSessionState Class from
 HttpSessionState Class
 Extension Methods
 Applies to
 See also

Links of HttpSessionState Class from


HttpSessionState Class

Namespace: System.Web.SessionState

Assembly: System.Web.dll

Provides access to session-state values as well as session-level settings and lifetime management methods.

public sealed class HttpSessionState :

Inheritance Object --> HttpSessionState

Implements ICollection IEnumerable


ASP.NET provides session-state management to enable you to store information associated with a unique browser session across multiple requests. You can store a collection of values referenced by a key name or by numerical index. Access to session values and functionality is available using the HttpSessionState class, which is accessible through the Session property of the current HttpContext, or the Session property of the Page.

Session data is associated with a specific browser session using a unique identifier. By default, this identifier is stored in a non-expiring session cookie in the browser, but you can also configure your application to store the session identifier in the URL by setting the cookieless attribute to true or UseUri in the sessionState element of your application configuration. You can have ASP.NET determine whether cookies are supported by the browser by specifying a value of UseDeviceProfile for the cookieless attribute. You can also have ASP.NET determine whether cookies are enabled for the browser by specifying a value of AutoDetect for the cookieless attribute. If cookies are supported when UseDeviceProfile is specified, or enabled when AutoDetect is specified, then the session identifier will be stored in a cookie; otherwise the session identifier will be stored in the URL.

Sessions are started during the first request and session values will persist as long as a new request is made by the browser before the number of minutes specified in the Timeout property pass. When a new session begins, the session Start event is raised. You can use this event to perform any additional work at the start of a session, such as setting default session values. When a session times out, the Abandon method is called, or the ASP.NET application is shut down, the session End event is raised. You can use this event to perform any necessary cleanup. The End event is raised only when the session state mode is set to InProc.

To improve performance, sessions that use cookies do not allocate session storage until data is actually stored in the Session object. For more information, see the SessionID property.

Session state does not persist across ASP.NET application boundaries. If a browser navigates to another application, the session information is not available to the new application.

Session values are stored in memory on the Web server, by default. You can also store session values in a SQL Server database, an ASP.NET state server, or a custom server. This enables you to preserve session values in cases where the ASP.NET or IIS process or the ASP.NET application restarts and to make session values available across all the servers in a Web farm. This behavior is configured by setting the mode attribute to a valid SessionStateMode value in the sessionState element of your application configuration. For more information, see Session-State Modes.

Alternatives to session state include application state (see the Application property) and the ASP.NET cache (see the System.Web.Caching namespace), which store variables that can be accessed by all users of an ASP.NET application; the ASP.NET profile (see the System.Web.Profile namespace), which persists user values in a data store without expiring them using a time-out; ASP.NET System.Web.UI.WebControls, which persist control values in the ViewState; Cookies; the QueryString property; and fields on an HTML form that are available from an HTTP POST using the Form collection. For more details on the differences between session state and other state-management alternatives, see ASP.NET State Management Recommendations.



Extension Methods

Applies to

.NET Framework: 4.8 4.7.2 4.7.1 4.7 4.6.2 4.6.1 4.6 4.5.2 4.5.1 4.5 4.0 3.5 3.0 2.0 1.1

See also



  1. Active Server Pages,, updated 20Dec2012
  2. ASP Overview,, updated 21Dec2012
  3. ASP Best Practices,, updated 15Apr2013
  4. ASP Built-in Objects,, updated 20Dec2012
  5. Response Object,, updated 20Dec2012
  6. Request Object,, updated 20Dec2012
  7. Server Object (IIS),, updated 20Dec2012
  8. Application Object (IIS),, updated 20Dec2012
  9. Session Object (IIS),, updated 20Dec2012
  10. ASPError Object,, updated 20Dec2012
  11. ObjectContext Object (IIS),, updated 20Dec2012
  12. Debugging Global.asa Files,, updated 15Apr2013
  13. How to: Debug Global.asa files,, updated 15Apr2013
  14. Calling COM Components from ASP Pages,, updated 15Apr2013
  15. IIS ASP Scripting Reference,, updated 15Apr2013
  16. ASP Keywords,, updated 15Apr2013
  17. Creating Simple ASP Pages,, updated 15Apr2013
  18. Including Files in ASP Applications,, updated 15Apr2013
  19. ASP Overview,, updated 15Apr2013
  20. FileSystemObject Object,, updated 14Mayr2013
  21., ADO Object Model, updated 15Apr2013
  22. ADO Fundamentals,, updated 14Mayr2013

ID: 190600007 Last Updated: 2019/6/7 Revision: Ref:


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