IHttpAsyncHandler, IRequiresSessionState, and IReadOnlySessionState Asynchronous Handler Issue

Here's a quick tip for getting access to Session state if you are using asynchronous http handlers. I've run into issues where System.Web.HttpContext.Current.Session did not contain any sessions variables. Didn't matter whether I used IRequiresSessionState or IReadOnlySessionState. I use a nice wrapper class for my session variables and just couldn't figure out why it wasn't working.

As it turns out, in my typical asynchronous logic, I had forgotten that my class accepted the current HttpContext passed into the handler.  Using the passed in HttpContext is what fixed my issue.  Figured I'd put this out there for anyone else who was using similar tactics and had the same session variable issue.

public class MyUploadClassHandler : IHttpAsyncHandler, IRequiresSessionState
  {
  
        public IAsyncResult BeginProcessRequest(HttpContext context, AsyncCallback cb, Object extraData)
        {
             var upload = new MyUploadAsyncClass(cb, context, extraData);
             upload.Start();
            return upload;
        }

        public void EndProcessRequest(IAsyncResult result)
        {
         }

        public void ProcessRequest(HttpContext context)
        {
           
        }

        public bool IsReusable
        {
             get
             {
                 return false;
            }
        }

}



class MyUploadAsyncClass : IAsyncResult
{
        private bool _completed;
        private Object _state;
        private AsyncCallback _callback;
        private HttpContext _context;

        bool IAsyncResult.IsCompleted { get { return _completed; } }
       WaitHandle IAsyncResult.AsyncWaitHandle { get { return null; } }
        Object IAsyncResult.AsyncState { get { return _state; } }
        bool IAsyncResult.CompletedSynchronously { get { return false; } }

        public MyUploadAsyncClass(AsyncCallback callback, HttpContext context, Object state)
        {
            _callback = callback;
            _context = context;
            _state = state;
            _completed = false;
        }

        public void Start()
        {
           ThreadPool.QueueUserWorkItem(new WaitCallback(StartAsyncTask), null);
        }

        private void StartAsyncTask(Object workItemState)
        {
             string citation = string.Empty;

             try
            {
                 _context.Response.StatusCode = 200;

                 var uploads = (List<UploadItem>)_context.Session["UploadItems"];

                 if (uploads == null || uploads.Count < 1)
                 {
                     _context.Response.Write("|No uploads found in session.");
                     return;
                 }
                 
                 _context.Response.Write("do some stuff");

             }
             catch (Exception ex)
             {
               Utility.HandleError(ex);
            }
            finally
            {
                _completed = true;
                 _callback(this);
            }

        }
    }