Dear Christian,

I am really thankful for your attention,
I wrote some jsp pages with servlets to read from and write on the data base 
using REST webservice
it works when I run a query that read a data, but it does not work when I run a query to insert a node:

public boolean insert(Vector<String> values) throws BaseXException  {
        Enumeration elnum = elems.elements();
        Enumeration valenum = values.elements();
        String elem;
        String val;
        String st = " insert node <" + parentElem + "> ";
        String res;
        String user="admin";
        String pass="admin";
         String encoded=Base64.encode(user+":"+pass);
        while (elnum.hasMoreElements()) {
            elem = elnum.nextElement().toString();
            val = valenum.nextElement().toString();
            st = st + " <" + elem + ">" + val + "</" + elem + "> ";
        }
        st = st + "</" + parentElem + ">" + " into //elib/" + tableName;

            res="<query xmlns='http://basex.org/rest'>\n"+
                " <text>"+st+"</text>\n"+
                "  <parameter name='wrap' value='yes'/>\n" +
                "</query>";
    // the res would be : 
   // <query xmlns='http://basex.org/rest'>
  // <text> insert node <user>  <name>khaledRefai</name>  // //<username>khaled89</username>   //<password>khaled</password> </user> 
 //into //elib/users</text>
//  <parameter name='wrap' value='yes'/>
//</query>
           try {
              conn = (HttpURLConnection) url.openConnection();
              conn.setDoOutput(true);
            conn.setRequestMethod("POST");
           conn.setRequestProperty("Content-Type", "application/xml");
             conn.setRequestProperty("Authorization", "Basic " + encoded);

            out = conn.getOutputStream();
           out.write(res.getBytes("UTF-8"));
           out.close();
                int code = conn.getResponseCode(); 
                System.out.println(conn.getResponseMessage());
                                        //it  print  "Bad Request"
                  if(code==200)
                     return true;
                 else
                     return false;


        } catch (IOException ex) {
return false;
        }
        
    }

thank you in advance