<?xml version="1.0" encoding="utf-8"?>
<flusso>
  <traccia><![CDATA[dati...]]></traccia>
  <traccia><![CDATA[dati...]]></traccia>
  <traccia><![CDATA[dati...]]></traccia>
</flusso>

[WebMethod]
    public void UploadFlusso(Stream stream)
    {
        using (XmlReader reader = XmlReader.Create(stream))
        {
            StringBuilder sb = new StringBuilder();

            reader.ReadStartElement("flusso");
            while (!reader.EOF)
            {
                
                reader.ReadStartElement("traccia");
                sb.Append(reader.ReadContentAsString());
               
                reader.ReadEndElement(); 
            }
            reader.ReadEndElement();
        }

        //scrive nel db...
    }