public string SendAccountPackage(Account oldAccount, Account newAccount, string keyword) { if (clientModel.HasFunction(FunctionType.UserSystem)) { while (sending) { Thread.Sleep(100); } sending = true; isReceive = false; AccountList sendList = new AccountList(); sendList.AddOldAndNewAccount(oldAccount, newAccount); AccountPackage sendPackage = new AccountPackage(sendList, keyword); string send = JsonSerializer.Serialize(sendPackage); Send(send); while (!isReceive) { Thread.Sleep(100); } sending = false; return(receiveMessage); } else { return("User System offline, please logoff."); } }