public string Execute()
 {
     if (request.HttpMethod.ToUpper().Equals("GET"))
     {
         string signature = request.QueryString[CommonEnum.SIGNATURE];
         string timestamp = request.QueryString[CommonEnum.TIMESTAMP];
         string nonce     = request.QueryString[CommonEnum.NONCE];
         if (CheckSignature.Check(signature, timestamp, nonce))
         {
             return(HttpContext.Current.Request.QueryString[CommonEnum.ECHOSTR]);
         }
         else
         {
             return(string.Empty);
         }
     }
     else
     {
         string     requestXml = RequestUtility.ReadRequest(request);
         ReqMsgBase reqMsg     = ReqMsgFactory.GetReqMsgEntity(XDocument.Parse(requestXml));
         return(ResponseMsg(reqMsg));
     }
 }