以下代码就是将一个定义好的xml文档发送至     http://www.zdbase.com，并从http://www.zdbase.com获取对应xml文档:           

                    XmlDocument doc = new XmlDocument();

                    doc.Load(AppDomain.CurrentDomain.BaseDirectory + "Xml\\SSORequest.xml");

                    doc.SelectSingleNode("sso/head/ctid").InnerText = Guid.NewGuid().ToString();

                    doc.SelectSingleNode("sso/body/appId").InnerText = ConfigurationManager.AppSettings["AppId"].ToString();

                    doc.SelectSingleNode("sso/body/token").InnerText = Request.QueryString["Token"].ToString();

                    byte[] data = Encoding.UTF8.GetBytes(doc.InnerXml);

                    HttpWebRequest request = (HttpWebRequest)HttpWebRequest.Create("http://www.zdbase.com");

                    request.Method = "POST";

                    request.ContentType = "text/xml";

                    request.ContentLength = data.Length;

                    using (Stream stream = request.GetRequestStream())
                    {

                        stream.Write(data, 0, data.Length);

                    }

  using (WebResponse wr = request.GetResponse())
                    {

                        using (StreamReader sr = new StreamReader(wr.GetResponseStream(), Encoding.UTF8))
                        {

                            //Response.Write(sr.ReadToEnd());
                            XmlDocument xmlRes = new XmlDocument();
                            xmlRes.LoadXml(sr.ReadToEnd());

                           //这里获得xml文档，可以像读取本地xml文档一样读取了

                         }

                    }