Migrate from Basic to MVVM and MEF Composable Patterns for a Silverlight Application - Part 3

using System;
using System.Windows;
using System.ServiceModel.DomainServices.Client;
using ProductRiaLib.Web.Services;

namespace ProductApp.Common
{
    public class DataAsyncHandlers
    {        
        public static void LoadQueryAsync<T>(ProductDomainContext context, EntityQuery<T> qry, object sender,
                                  EventHandler<QueryResultsArgs<T>> queryResultEvent) where T : Entity
        {
            // Execute the load and wait for the asyn operation to get the 
            // dataset back in the callback argument
            context.Load(qry, LoadBehavior.RefreshCurrent, r =>
            {
                if (queryResultEvent != null)
                {
                    try
                    {
                        if (r.HasError)
                        {
                            queryResultEvent(sender, new QueryResultsArgs<T>(r.Error));
                            r.MarkErrorAsHandled();
                        }
                        else
                        {                            
                            queryResultEvent(sender, new QueryResultsArgs<T>(r.Entities));
                        }
                    }
                    catch (Exception ex)
                    {
                        queryResultEvent(sender, new QueryResultsArgs<T>(ex));
                    }
                }
            }, null);
        }

        public static void SaveChangesAsync(ProductDomainContext context, object sender, 
                                EventHandler<SubmitOperationArgs> saveChangesCompleteEvent)
        {
            // Execute the submission and wait for the asyn operation to get the 
            // status in the callback argument
            context.SubmitChanges(s =>
            {
                if (saveChangesCompleteEvent != null)
                {
                    try
                    {
                        Exception ex = null;
                        if (s.HasError)
                        {
                            ex = s.Error;
                            s.MarkErrorAsHandled();
                        }
                        saveChangesCompleteEvent(sender, new SubmitOperationArgs(s, ex));
                    }
                    catch (Exception ex)
                    {
                        saveChangesCompleteEvent(sender, new SubmitOperationArgs(ex));
                    }
                }
            }, null);
        }
    }
}