public string InitialMessage;
        private string knowledgeBaseId;
        private string subscriptionKey;

        public override async Task StartAsync(IDialogContext context)
        {
            var type = this.GetType();
            var qNaServiceAttribute = type.GetCustomAttributes<QnAMakerServiceAttribute>().FirstOrDefault();
            subscriptionKey = qNaServiceAttribute.SubscriptionKey;
            knowledgeBaseId = qNaServiceAttribute.KnowledgeBaseId;


            if (!string.IsNullOrEmpty(InitialMessage))
            {
                await HandleMessage(context, InitialMessage);
            }
            else
            {
                context.Wait(MessageReceived);
            }
        }

        private async Task HandleMessage(IDialogContext context, string queryText)
        {
            var response = await GetQnAMakerResponse(queryText, knowledgeBaseId, subscriptionKey);

            if (HandlerByMaximumScore == null)
            {
                HandlerByMaximumScore =
                    new Dictionary<QnAMakerResponseHandlerAttribute, QnAMakerResponseHandler>(GetHandlersByMaximumScore());
            }

            if (response.Score == 0)
            {
                await NoMatchHandler(context, queryText);
            }
            else
            {
                var applicableHandlers = HandlerByMaximumScore.OrderBy(h => h.Key.MaximumScore).Where(h => h.Key.MaximumScore > response.Score);
                var handler = applicableHandlers.Any() ? applicableHandlers.First().Value : null;

                if (handler != null)
                {
                    await handler.Invoke(context, queryText, response);
                }
                else
                {
                    await DefaultMatchHandler(context, queryText, response);
                }
            }
        }

        private async Task<QnAMakerResult> GetQnAMakerResponse(string query, string knowledgeBaseId, string subscriptionKey)
        {
            string responseString = string.Empty;

            var knowledgebaseId = knowledgeBaseId; // Use knowledge base id created.
            var qnamakerSubscriptionKey = subscriptionKey; //Use subscription key assigned to you.

            //Build the URI
            Uri qnamakerUriBase = new Uri("https://westus.api.cognitive.microsoft.com/qnamaker/v1.0");
            var builder = new UriBuilder($"{qnamakerUriBase}/knowledgebases/{knowledgebaseId}/generateAnswer");

            //Add the question as part of the body
            var postBody = $"{{\"question\": \"{query}\"}}";

            //Send the POST request
            using (WebClient client = new WebClient())
            {
                //Set the encoding to UTF8
                client.Encoding = System.Text.Encoding.UTF8;

                //Add the subscription key header
                client.Headers.Add("Ocp-Apim-Subscription-Key", qnamakerSubscriptionKey);
                client.Headers.Add("Content-Type", "application/json");
                responseString = client.UploadString(builder.Uri, postBody);
            }

            //De-serialize the response
            QnAMakerResult response;
            try
            {
                response = JsonConvert.DeserializeObject<QnAMakerResult>(responseString);
                return response;
            }
            catch
            {
                throw new Exception("Unable to deserialize QnA Maker response string.");
            }
        }