RoyalMailMessage.cs

using System.ServiceModel.Channels;
using System.Xml;

namespace RoyalMail
{
    public class RoyalMailMessage : Message
    {
        private readonly Message message;

        public RoyalMailMessage(Message message)
        {
            this.message = message;
        }
        public override MessageHeaders Headers => message.Headers;

        public override MessageProperties Properties => message.Properties;

        public override MessageVersion Version => message.Version;

        protected override void OnWriteStartBody(XmlDictionaryWriter writer)
        {
            writer.WriteStartElement("soapenv","Body", "http://schemas.xmlsoap.org/soap/envelope/");
        }

        protected override void OnWriteStartHeaders(XmlDictionaryWriter writer)
        {
            writer.WriteStartElement("soapenv", "Header", null);
        }
        protected override void OnWriteBodyContents(XmlDictionaryWriter writer)
        {
            message.WriteBodyContents(writer);
        }

        protected override void OnWriteStartEnvelope(XmlDictionaryWriter writer)
        {
            writer.WriteStartElement("soapenv", "Envelope", "http://schemas.xmlsoap.org/soap/envelope/");
            writer.WriteAttributeString("xmlns", "oas", null, "http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-secext-1.0.xsd");
            writer.WriteAttributeString("xmlns", "v2", null, "http://www.royalmailgroup.com/api/ship/V2");
            writer.WriteAttributeString("xmlns", "v1", null, "http://www.royalmailgroup.com/integration/core/V1");
            writer.WriteAttributeString("xmlns", "xsi", null, "http://www.w3.org/2001/XMLSchema-instance");
            writer.WriteAttributeString("xmlns", "xsd", null, "http://www.w3.org/2001/XMLSchema");            
        }
    }
}