private void OnJoinGroupComplete(object sender, JoinGroupRequestEventArgs e)
        {
            Dispatcher.BeginInvoke(() => {
                if (e.GroupId != Group.ResourceId)
                    return;

                ProgressView.Visibility = Visibility.Collapsed;
                StatusLabel.Text = AppResources.GroupRequestSentText;
                doneButton.IsEnabled = true;

            });
        }
        public void SendJoinGroupRequestAsync(string groupId, string message, Dictionary<string, string> parameters = null)
        {
            string timestamp = DateTimeUtils.GetTimestamp();
            string nonce = Guid.NewGuid().ToString().Replace("-", null);

            Dictionary<string, string> paramDict = new Dictionary<string, string>();
            paramDict["method"] = "flickr.groups.joinRequest";
            paramDict["format"] = "json";
            paramDict["nojsoncallback"] = "1";
            paramDict["oauth_consumer_key"] = consumerKey;
            paramDict["oauth_nonce"] = nonce;
            paramDict["oauth_signature_method"] = "HMAC-SHA1";
            paramDict["oauth_timestamp"] = timestamp;
            paramDict["oauth_token"] = AccessToken;
            paramDict["oauth_version"] = "1.0";
            paramDict["group_id"] = groupId;
            paramDict["message"] = message;

            if (parameters != null)
            {
                foreach (var entry in parameters)
                {
                    paramDict[entry.Key] = entry.Value;
                }
            }

            string signature = OAuthCalculateSignature("POST", "https://api.flickr.com/services/rest/", paramDict, AccessTokenSecret);
            paramDict["oauth_signature"] = signature;

            DispatchPostRequest("POST", "https://api.flickr.com/services/rest/", paramDict,
                (response) =>
                {
                    bool success = true;
                    string errorMessage = "";

                    try
                    {
                        JObject json = JObject.Parse(response);
                        string status = json["stat"].ToString();
                        if (status != "ok")
                        {
                            success = false;
                            errorMessage = json["message"].ToString();
                        }
                    }
                    catch (Exception e)
                    {
                        Debug.WriteLine(e.Message);

                        success = false;
                    }

                    if (!success)
                    {
                        var exceptionEvt = new JoinGroupRequestExceptionEventArgs();
                        exceptionEvt.GroupId = groupId;
                        exceptionEvt.Message = errorMessage;
                        JoinGroupRequestException.DispatchEvent(this, exceptionEvt);
                    }
                    else
                    {
                        var evt = new JoinGroupRequestEventArgs();
                        evt.GroupId = groupId;
                        JoinGroupRequestComplete.DispatchEvent(this, evt);
                    }

                }, (ex) =>
                {
                    var exceptionEvt = new JoinGroupRequestExceptionEventArgs();
                    exceptionEvt.GroupId = groupId;
                    exceptionEvt.Message = "Unknown network error";
                    JoinGroupRequestException.DispatchEvent(this, exceptionEvt);
                });


        }