public async Task RegisterObservableServiceAsync(GatewayRequest request)
        {
            try
            {
                // Validates parameter
                if (string.IsNullOrWhiteSpace(request?.Topic) ||
                    (request.ObservableEntityId?.ServiceUri == null))
                {
                    throw new ArgumentException($"Parameter {nameof(request)} is null or invalid.", nameof(request));
                }

                // Gets service proxy
                IClientObservableService proxy = GetServiceProxy(
                    request.ObservableEntityId.PartitionKey,
                    request.ObservableEntityId.ServiceUri);
                if (proxy == null)
                {
                    throw new ApplicationException("The ServiceProxy cannot be null.");
                }

                // Invokes actor using proxy
                ServiceEventSource.Current.Message(
                    $"Registering observable...\r\n[Observable]: {request.ObservableEntityId}\r\n[Publication]: Topic=[{request.Topic}]");
                await proxy.RegisterObservableServiceAsync(request.Topic);
            }
            catch (AggregateException ex)
            {
                if (!(ex.InnerExceptions?.Count > 0))
                {
                    throw new HttpResponseException(this.Request.CreateErrorResponse(HttpStatusCode.NotFound, ex.Message));
                }
                foreach (Exception exception in ex.InnerExceptions)
                {
                    ServiceEventSource.Current.Message(exception.Message);
                }
                throw new HttpResponseException(this.Request.CreateErrorResponse(HttpStatusCode.NotFound, ex.Message));
            }
            catch (Exception ex)
            {
                ServiceEventSource.Current.Message(ex.Message);
                throw new HttpResponseException(this.Request.CreateErrorResponse(HttpStatusCode.NotFound, ex.Message));
            }
        }