String st = "<query xmlns='http://basex.org/rest'>"+
 "<text> insert node <user>  <name>qusai</name> "+
"<username>qu</username>  <password>qu</password>"+
" </user> into //elib/users</text>"+
  "<parameter name='wrap' value='yes'/></query>"
 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();
System.out.println(conn.getResponseMessage());

and the result  from server is : Bad Request
????
any answer