Cache System in Silverlight 5 RIA Application - Part 2 - Data write

using System;
using System.Collections.Generic;
using System.Linq;
using System.Net;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Animation;
using System.Windows.Shapes;
using SilverlightClient.Common;
using SilverlightClient.Core;
using SilverlightClient.Core.ViewModels;

namespace SilverlightClient
{
    public partial class MainPage : UserControl
    {
        private MainViewModel viewModel;

        public MainPage()
        {
            InitializeComponent();

            SetDataContext();
        }

        void SetDataContext()
        {
            viewModel = new MainViewModel();
            this.DataContext = viewModel;
        }

        private void LoadUser(object sender, RoutedEventArgs e)
        {
            ModelManager.Instance.Load(this.viewModel, OperationType.LOAD_USER, new Object[] {"Username", "Password"});
        }

        private void Reset(object sender, RoutedEventArgs e)
        {
            viewModel.UserContext = null;
        }

        private void SaveUser(object sender, RoutedEventArgs e)
        {
            var ucToSave = this.viewModel.UserContext.Clone();
            ucToSave.Email = txtEmail.Text;

            ModelManager.Instance.Write(this.viewModel, OperationType.WRITE_USER, new Object[] { ucToSave });
        }

        private void SaveChanges(object sender, RoutedEventArgs e)
        {
            ModelManager.Instance.WritePendingChanges();
        }

        private void ForceWrite(object sender, RoutedEventArgs e)
        {
            var ucToSave = this.viewModel.UserContext.Clone();
            ucToSave.Email = txtEmail.Text;

            ModelManager.Instance.WriteForce(this.viewModel, OperationType.WRITE_USER, new Object[] { ucToSave }, true);
        }

        private void SaveMvvm(object sender, RoutedEventArgs e)
        {
            ModelManager.Instance.WriteForce(this.viewModel, OperationType.WRITE_USER, new Object[] { this.viewModel.UserContext }, false);
        }
    }
}