三层架构

哪位大侠能给我解释一下这个是什么意思，麻烦给具体解释一下语句
--------------------编程问答-------------------- 看不清。。。直接上传代码不好上传个这么大的图片。。

--------------------编程问答-------------------- namespace ProjectManager.BLL.LM.EM
{
    /// <summary>
    /// EmployeeOperate
    /// </summary>
    public class EmployeeOperate : IEmployeeOperate
    {
        private const string PAGEID = "EmployeeOperate";

        #region EmployeeOperate Members


        public  DataSet GetEmployeeInfoList()
        {
            try
            {
                return DbHelper.ExecuteDataSet(PAGEID, "Sql001");
            }
            catch (Exception ex)
            {
                Handler.WriteErrorLog(ex.ToString());
                throw ;
            }

        }

        public void InsertEmployee(Entity_HX_EMPLOYEE obj, Entity_HX_ROLE obj1)
        {

            Database dbKanban = null;
            DbConnection con = null;
            DbTransaction trans = null;

            ArrayList paramlist = Handler.GetParamList(obj);
            ArrayList paramlist1 = Handler.GetParamList(obj1);

            //remove param id
            paramlist1.RemoveAt(0);
            try
            {
                dbKanban = DatabaseFactory.CreateDatabase();
                con = dbKanban.CreateConnection();
                con.Open();
                trans = con.BeginTransaction();
                DbHelper.ExecuteNonQuery(PAGEID, "Sql002", paramlist);
                DbHelper.ExecuteNonQuery(PAGEID, "Sql005", paramlist1);
                trans.Commit();
            }
            catch(SqlException ex)
            {
                trans.Rollback();
                if (ex.ErrorCode == -2146232060)
                {
                    throw new ThrowSoapException().GetSoapExceptionInstance(ex.Message, BusinessConst.EXCEPTION_PRIMARY_REPEAT);
                }
            }

            //Save Employee Logo To Server
            UpLoadEmployeeLogo(paramlist);

            //UpdateEmployeeImage
           // UpdateEmployeeImage(paramlist);
        }

        private void UpLoadEmployeeLogo(ArrayList paramlist)
        {

            byte[] imgLogo = paramlist[paramlist.Count - 2] as byte[];
            string filePath = HttpContext.Current.Server.MapPath(".") + "\\Logo\\";
            if (!Directory.Exists(filePath))
            {
                Directory.CreateDirectory(filePath);
            }
            string employeeId = paramlist[0] as string;
            string fileName = filePath + employeeId + ".jpg";
            if (File.Exists(fileName))
            {
                FileInfo fn = new FileInfo(fileName);
                if (fn.IsReadOnly)
                {
                    fn.IsReadOnly = false;
                }
            }
            File.WriteAllBytes(fileName, imgLogo);
        } --------------------编程问答-------------------- 不会每句都要解释吧，还是？

补充：.NET技术 ,  C#