Enterprise Application Architecture with LINQ to SQL

using System;
using System.Linq;
using System.Collections.Generic;
using System.Text;
using System.Xml;
using System.Data;
using System.Data.Linq;
using System.Data.SqlClient;
using Northwind.Data;
using Northwind.Data.DTO;

namespace DLinqContext.Factory
{
    /// <summary>
    /// Uses the mapping file generated by SqlMetal.exe but loads it just once in 
    /// the app domain's life cycle.
    /// </summary>
    public static class SessionSingletonMappingSrc
    {
        static readonly MappingSource _mappingSrc;

        static SessionSingletonMappingSrc()
        {
            _mappingSrc = CreateMappingSource();
        }

        public static DataContext CreateDataContext()
        {
            return new NorthwindContext(CreateConnection(), _mappingSrc);
        }

        static IDbConnection CreateConnection()
        {
            return new SqlConnection(@"server=.; initial catalog=northwind; integrated security=SSPI");
        }

        static MappingSource CreateMappingSource()
        {
            return XmlMappingSource.FromReader(new XmlTextReader("northwindMapping.xml"));
        }
    }
}