public CategoryInstanceViewModel CategoryInstance(CategoryInstanceInputModel inputModel)
        {
            //initialize the dropdownlist values
            string myCatName = inputModel.CategoryName;
            var performanceCounterInstanceNames = _performanceMonitorService.GetInstanceNames(myCatName);

            var instanceList = performanceCounterInstanceNames.Select(c => new SelectListItem
            {
                Text = c.ToString(),
                Value = c.ToString()
            });

            bool accessibleValue = true;
            if (performanceCounterInstanceNames.Count == 0)
            {
                _notifier.Error(T("Error: Category and instances not accessible"));
                accessibleValue = false;
            }
            CategoryInstanceViewModel viewModel = new CategoryInstanceViewModel()
            {
                InstanceList = new SelectList(instanceList, "Value", "Text", inputModel.InstanceName),
                Accessible = accessibleValue
            };

            return viewModel;
        }
 //[HandleError, OrchardAuthorization(PermissionName = OrchardPermissionStrings.SiteOwner)]
 public ActionResult CategoryInstance(string selectedCategoryName)
 {
     CategoryInstanceInputModel inputModel = new CategoryInstanceInputModel();
     inputModel.CategoryName = selectedCategoryName;
     CategoryInstanceViewModel viewModel = _performanceMonitorWorkerService.CategoryInstance(inputModel);
     viewModel.CategoryName = selectedCategoryName;
     if (viewModel.Accessible == false)
     {
         return RedirectToAction("Category");
     }
     return View(viewModel);
 }
        //[HandleError, OrchardAuthorization(PermissionName = ApplicationFrameworkPermissionStrings.EditConfigurationSettings)]
        public ActionResult CategoryInstancePost(CategoryInstancePostInputModel inputModel)
        {
            if (!ModelState.IsValid)
            {
                CategoryInstanceInputModel catInstanceInputModel = new CategoryInstanceInputModel();
                catInstanceInputModel.CategoryName = inputModel.CategoryName;
                CategoryInstanceViewModel viewModel = _performanceMonitorWorkerService.CategoryInstance(catInstanceInputModel);
                return View("CategoryInstance", viewModel);
            }

            string categoryName = inputModel.CategoryName;
            string instanceName = inputModel.InstanceName;
            return RedirectToAction("Edit", "PerformanceMonitor", new { selectedCategoryName = categoryName, selectedInstanceName = instanceName });
        }