static void proxy_GetAppSettingsCompleted(object sender, GetAppSettingsCompletedEventArgs e)
        {
            Guid callerKey = (Guid)e.UserState;

            if (_callbacks.ContainsKey(callerKey))
            {
                AppSettings itemSource = e.Result;
                ((GetAppSettingsCallBack)_callbacks[callerKey]).Invoke(itemSource);

                _callbacks.Remove(callerKey);
            }
        }
        static void proxy_GetAppSettingsCompleted(object sender, GetAppSettingsCompletedEventArgs e)
        {
            Guid callerKey = (Guid)e.UserState;
            if (_callbacks.ContainsKey(callerKey))
            {
                AppSettings itemSource = e.Result;
                ((GetAppSettingsCallBack)_callbacks[callerKey]).Invoke(itemSource);

                _callbacks.Remove(callerKey);
            }
        }