Friday, August 26, 2016

Sitecore MVC Session handling

It all started when we had session timeout and it resulted in error page. Yes session checks were not handled properly.All I was looking to solve this trivial problem with quick code fix but it turn out to be a bit of research again. This is indeed a sitecore world, where every request surface with filters, route and action. Each request is fragmented as we had controller rendering to serve all our dynamic data and transaction commits.

****Register Global Filter to check for session. 
This will not work as there are some workflow pages which are not session or authorization dependent. It bit the purpose.

Next thought of handling this in SessionEnd pipeline.
GlobalFilters.Filters.Add(new SessionExpireAttribute());

****SessionEnd Pipeline Response.Redirect and Server.Transfer will not work!

Session_End is fired internally by the server, based on an internal timer. And thus there is no HttpRequest associted when that happens. That is why Response.Redirect or Server.Transfer does not make sense and will not work. 

**** SessionEnd is not fired if session mode is outproc.
It will be fired only when using session mode set as inproc or Custom.

****Solution: Not elegant but it worked.
Let the session timeout and then eventually it will be send to the path of common error handling module where we can take appropriate action to redirect it to login page or some information page to notify user about session timeout.
 
****Post Session Timeout-  User action server side event.
****Post Session Timeout- User action cliend side event fired.(Check for IsAjaxRequest)
 public class RenderingControllerExceptionProcessor : ExceptionProcessor
{  
    public override void Process(ExceptionArgs args)
    {
            var userContext = SessionService.Get();
            if (userContext == null)
                if (args.ExceptionContext.HttpContext.Request.IsAjaxRequest())
                {
             //send something to response result.
                    args.ExceptionContext.Result = new JsonResult
                    {
                        Data = new
                        {
                            Error = "NotAuthorized",
                            LogOnUrl = "/login"
                        },
                        JsonRequestBehavior = JsonRequestBehavior.AllowGet
                    };
                }
                else
                {
                    WebUtil.RedirectToLoginPage();
                }
   }
}
OR
 private bool IsSessionExpired()
        {
            if (HttpContext.Current.Session != null)
            {
                
                if ( HttpContext.Current.Session.IsNewSession)
                {
                    //Note: Below code fails for Custom session.Works for Inproc
                    string cookieHeaders = HttpContext.Current.Request.Headers["Cookie"];

                    if ((null != cookieHeaders) &&
                       (cookieHeaders.IndexOf("ASP.NET_SessionId", StringComparison.Ordinal) >= 0))
                    
                        // IsNewSession is true, but session cookie exists,
                        // so, ASP.NET session is expired
                        return true;
                    
                }
                // Session is not expired and function will return false,
                // could be new session, or existing active session
                return false;
            }
            return false;
        }
The only solution is to handle through global application error event in sitecore rendering.


Always Consider these values when dealing with session:.

  1. Polling interval
  2. Compression
  3. Session type
  4. SlidingExpiration

Side Note:
If your worker process restarts and it causes your cache to clear, think of using agent to ping Keepalive.aspx.
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