SOAP request Multicast over UDP

I want to use C# UDPClient class to multicast soap request over network, I can multicast simple strings using UDPclient class but how I will do it with Soap messages ?

 public void SendProbe()
    {
        UdpClient sock = new UdpClient();
        IPEndPoint iep = 开发者_如何学运维new IPEndPoint(IPAddress.Parse("239.255.255.250"), 3702);
        // I want create soap message here to Multicast using UdpClient
        //
        //
        byte[] data = Encoding.ASCII.GetBytes("This is a test message");
        sock.Send(data, data.Length, iep);
        sock.Close();            
    }

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Soap servers usually listen on TCP ports.

Are you sure the soap servers you're targeting are listening for UDP traffic?