xml post(C#)

xmlpost by HttpWebRequest:
protected string PostXmlToURL(string url,string data)
{
    HttpWebRequest hwr = (HttpWebRequest)HttpWebRequest.Create(url);
    hwr.Method = "POST";
    Stream stream = hwr.GetRequestStream();
    StreamWriter sw = new StreamWriter(stream, System.Text.Encoding.UTF8);
    sw.Write(data);
    sw.Close();
    stream = hwr.GetResponse().GetResponseStream();
    StreamReader sr = new StreamReader(stream);
    string result = sr.ReadToEnd();
    sr.Close();
    return result;           
}
xmlpost by XMLHTTP:
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   StreamReader sr=new StreamReader(Server.MapPath(XMLPathFull));
   MSXML2.XMLHTTPClass xmlHttp = new MSXML2.XMLHTTPClass();   
   xmlHttp.open("post",strURL,false,"","");  
   xmlHttp.setRequestHeader  ("Content-type","text/xml;charset=UTF-8");
   xmlHttp.send(sr.ReadToEnd());
   //µÃµ½response
   string backxmlstring=xmlHttp.responseText.ToString();
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   byte[]   buf   =   Request.BinaryRead(Request.ContentLength);   
   string   str   =   System.Text.Encoding.UTF8.GetString(buf);  
xmlpost by js:
<script language="javascript" type="text/javascript">
    function PostXml(url, data) {
        var xmlhttp = new ActiveXObject("Msxml2.XMLHTTP");
        xmlhttp.Open("POST", url, false);
        xmlhttp.SetRequestHeader("Content-Type", "application/x-www-form-urlencoded");
        xmlhttp.SetRequestHeader("Content-Length", d