Export To Excel in lightswitch 2011 for web

namespace Service
{
    using System.ServiceModel.DomainServices.Hosting;
    using System.ServiceModel.DomainServices.Server;
    using System.Data.SqlClient;
    using System.Data;
    using Microsoft.Office.Interop.Excel;
    using System.Runtime.InteropServices;

    // TODO: Create methods containing your application logic.
    [EnableClientAccess()]
    public class MyDomainService : DomainService
    {
        public int ExportToExcel()
        {
            DataSet ds = new DataSet();
            using (SqlConnection connection = new SqlConnection(@"
                        your_db_connection_string;"))
            {
                connection.Open();
                using (SqlCommand command = new SqlCommand("Select * From Country", connection))
                {
                    using (SqlDataAdapter adapter = new SqlDataAdapter(command))
                    {
                        adapter.Fill(ds);
                        if (ds != null)
                        {
                            if (ds.Tables.Count > 0)
                            {
                                Application ExcelApp = new Application();
                                Workbook ExcelWorkBook = null;
                                Worksheet ExcelWorkSheet = null;
 
                                ExcelApp.Visible = true;
                                ExcelWorkBook = ExcelApp.Workbooks.Add(XlWBATemplate.xlWBATWorksheet);
                                ExcelWorkSheet = ExcelWorkBook.Worksheets[1];

 
                                int count = 1;
                                foreach (DataRow row in ds.Tables[0].Rows)
                                {
                                    ExcelWorkSheet.Cells[count, 1] = row["CountryName"].ToString();
                                    count++;
                                }
                                ExcelWorkBook.SaveAs(string.Format(@"c:\temp\{0}.xlsx", System.Guid.NewGuid()));
                                ExcelWorkBook.Close();
                                ExcelApp.Quit();
                                Marshal.ReleaseComObject(ExcelWorkSheet);
                                Marshal.ReleaseComObject(ExcelWorkBook);
                                Marshal.ReleaseComObject(ExcelApp);
                            }
                        }
                    }
                }
            }
            return 1;
        }
    }
}

partial void ExportToExcel_Execute()
{
            Dispatchers.Main.BeginInvoke(() =>
            {
                
                MyDomainContext context = new MyDomainContext();
                InvokeOperation<int> invoke = context.ExportToExcel(OpCompleted, null);
            });
}
private void OpCompleted(InvokeOperation<int> invokeOp)
{
            if (!invokeOp.HasError)
            {
                this.ShowMessageBox(invokeOp.Value.ToString());
            }
}

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