You need to use the xsd.exe tool which gets installed with the Windows SDK into a directory something similar to:

C:\Program Files\Microsoft SDKs\Windows\v6.0A\bin

And on 64-bit computers:

C:\Program Files (x86)\Microsoft SDKs\Windows\v6.0A\bin

And on Windows 10 computers:

C:\Program Files (x86)\Microsoft SDKs\Windows\v7.0A\bin

On the first run, you use xsd.exe and you convert your sample XML into a XSD file (XML schema file):

xsd yourfile.xml

This gives you yourfile.xsd, which in a second step, you can convert again using xsd.exe into a C# class:

xsd yourfile.xsd /c

This should give you a file yourfile.cs which will contain a C# class that you can use to deserialize the XML file you're getting - something like:

XmlSerializer serializer = new XmlSerializer(typeof(msg));
msg resultingMessage = (msg)serializer.Deserialize(new XmlTextReader("yourfile.xml"));

Should work pretty well for most cases.

Update: the XML serializer will take any stream as its input - either a file or a memory stream will be fine:

XmlSerializer serializer = new XmlSerializer(typeof(msg));
MemoryStream memStream = new MemoryStream(Encoding.UTF8.GetBytes(inputString));
msg resultingMessage = (msg)serializer.Deserialize(memStream);

or use a StringReader:

XmlSerializer serializer = new XmlSerializer(typeof(msg));
StringReader rdr = new StringReader(inputString);
msg resultingMessage = (msg)serializer.Deserialize(rdr);

You have two possibilities.

Method 1. XSD tool


Suppose that you have your XML file in this location C:\path\to\xml\file.xml
  1. Open Developer Command Prompt
    You can find it in Start Menu > Programs > Microsoft Visual Studio 2012 > Visual Studio Tools Or if you have Windows 8 can just start typing Developer Command Prompt in Start screen
  2. Change location to your XML file directory by typing cd /D "C:\path\to\xml"
  3. Create XSD file from your xml file by typing xsd file.xml
  4. Create C# classes by typing xsd /c file.xsd

And that's it! You have generated C# classes from xml file in C:\path\to\xml\file.cs

Method 2 - Paste special


Required Visual Studio 2012+ with .Net Framework >= 4.5 as project target and 'Windows Communication Foundation' individual component installed
  1. Copy content of your XML file to clipboard
  2. Add to your solution new, empty class file (Shift+Alt+C)
  3. Open that file and in menu click Edit > Paste special > Paste XML As Classes
    enter image description here

And that's it!

Usage


Usage is very simple with this helper class:

using System;
using System.IO;
using System.Web.Script.Serialization; // Add reference: System.Web.Extensions
using System.Xml;
using System.Xml.Serialization;

namespace Helpers
{
    internal static class ParseHelpers
    {
        private static JavaScriptSerializer json;
        private static JavaScriptSerializer JSON { get { return json ?? (json = new JavaScriptSerializer()); } }

        public static Stream ToStream(this string @this)
        {
            var stream = new MemoryStream();
            var writer = new StreamWriter(stream);
            writer.Write(@this);
            writer.Flush();
            stream.Position = 0;
            return stream;
        }


        public static T ParseXML<T>(this string @this) where T : class
        {
            var reader = XmlReader.Create(@this.Trim().ToStream(), new XmlReaderSettings() { ConformanceLevel = ConformanceLevel.Document });
            return new XmlSerializer(typeof(T)).Deserialize(reader) as T;
        }

        public static T ParseJSON<T>(this string @this) where T : class
        {
            return JSON.Deserialize<T>(@this.Trim());
        }
    }
}

All you have to do now, is:

    public class JSONRoot
    {
        public catalog catalog { get; set; }
    }
    // ...

    string xml = File.ReadAllText(@"D:\file.xml");
    var catalog1 = xml.ParseXML<catalog>();

    string json = File.ReadAllText(@"D:\file.json");
    var catalog2 = json.ParseJSON<JSONRoot>();

Try this method to Convert Xml to an object. It is made for exactly what you are doing:

protected T FromXml<T>(String xml)
{
    T returnedXmlClass = default(T);

    try
    {
        using (TextReader reader = new StringReader(xml))
        {
            try
            {
                returnedXmlClass = 
                    (T)new XmlSerializer(typeof(T)).Deserialize(reader);
            }
            catch (InvalidOperationException)
            {
                // String passed is not XML, simply return defaultXmlClass
            }
        }
    }
    catch (Exception ex)
    {
    }

    return returnedXmlClass ;        
}

Call it using this code:

YourStrongTypedEntity entity = FromXml<YourStrongTypedEntity>(YourMsgString);