using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Xml.Serialization;

using System.Xml;

using System.IO;

using System.Diagnostics;

using System.Collections.ObjectModel;

using System.Threading;

using System.ComponentModel;

using System.Xml.Linq;

using System.Reflection;

using System.Data;

using System.Xml.Schema;

using System.Text.RegularExpressions;

using System.Net;

using System.Xml.XPath;

using System.Globalization;

using System.ComponentModel.DataAnnotations;

using System.Collections;

using System.Runtime.InteropServices;

​

    public abstract class Shape

    {

    }

​

    public class Triangle : Shape

    {

    }

​

    public class Square : Shape

    {

    }

​

    public class Room

    {

        [XmlElement("DoorSquare", Type = typeof(Square)), XmlElement("DoorTriangle", Type = typeof(Triangle))]  

        public Shape Door { get; set; }

        [XmlElement("WindowSquare", Type = typeof(Square)), XmlElement("WindowTriangle", Type = typeof(Triangle))]  

        public Shape Window { get; set; }

    }

​

    public class Program

    {

        public static void Main()

        {

            var room = new Room

            {

                Door = new Triangle(),

                Window = new Square(),

            };

            var xml = room.GetXml(true);

            Console.WriteLine(xml);

        }

    }

​

    public static class XmlSerializationHelper

    {

        public static T LoadFromXML<T>(this string xmlString)

        {

            using (StringReader reader = new StringReader(xmlString))

            {

                return (T)new XmlSerializer(typeof(T)).Deserialize(reader);

            }

        }

​

        public static string GetXml<T>(this T obj, bool omitStandardNamespaces = false)

        {

            XmlSerializerNamespaces ns = null;

            if (omitStandardNamespaces)

            {

                ns = new XmlSerializerNamespaces();

                ns.Add("", ""); // Disable the xmlns:xsi and xmlns:xsd lines.

            }           

            using (var textWriter = new StringWriter())

            {

                var settings = new XmlWriterSettings() { Indent = true }; // For cosmetic purposes.

                using (var xmlWriter = XmlWriter.Create(textWriter, settings))

                    new XmlSerializer(obj.GetType()).Serialize(xmlWriter, obj, ns);

                return textWriter.ToString();

            }

        }

    }