public Task <AirbrakeResponse> NotifyAsync(Exception exception, IHttpContext context = null)
        {
            if (string.IsNullOrEmpty(config.ProjectId))
            {
                throw new Exception("Project Id is required");
            }

            if (string.IsNullOrEmpty(config.ProjectKey))
            {
                throw new Exception("Project Key is required");
            }

            // Task-based Asynchronous Pattern (https://msdn.microsoft.com/en-us/library/hh873177.aspx)
            var tcs = new TaskCompletionSource <AirbrakeResponse>();

            try
            {
                if (Utils.IsIgnoredEnvironment(config.Environment, config.IgnoreEnvironments))
                {
                    var response = new AirbrakeResponse {
                        Status = RequestStatus.Ignored
                    };
                    tcs.SetResult(response);
                    return(tcs.Task);
                }

                var noticeBuilder = new NoticeBuilder();
                noticeBuilder.SetErrorEntries(exception);
                noticeBuilder.SetConfigurationContext(config);

                if (context != null)
                {
                    noticeBuilder.SetHttpContext(context, config);
                }

#if NET45
                noticeBuilder.SetEnvironmentContext(Dns.GetHostName(), Environment.OSVersion.VersionString, "C#/NET45");
#elif NETSTANDARD1_4
                // TODO: check https://github.com/dotnet/corefx/issues/4306 for "Environment.MachineName"
                noticeBuilder.SetEnvironmentContext("", RuntimeInformation.OSDescription, "C#/NETCORE");
#endif
                var notice = noticeBuilder.ToNotice();

                if (filters.Count > 0)
                {
                    notice = Utils.ApplyFilters(notice, filters);
                }

                if (notice == null)
                {
                    var response = new AirbrakeResponse {
                        Status = RequestStatus.Ignored
                    };
                    tcs.SetResult(response);
                    return(tcs.Task);
                }

                var request = httpRequestHandler.Get();

                request.ContentType = "application/json";
                request.Accept      = "application/json";
                request.Method      = "POST";

                request.GetRequestStreamAsync().ContinueWith(requestStreamTask =>
                {
                    if (requestStreamTask.IsFaulted)
                    {
                        if (requestStreamTask.Exception != null)
                        {
                            tcs.SetException(requestStreamTask.Exception.InnerExceptions);
                        }
                    }
                    else if (requestStreamTask.IsCanceled)
                    {
                        tcs.SetCanceled();
                    }
                    else
                    {
                        using (var requestStream = requestStreamTask.Result)
                            using (var requestWriter = new StreamWriter(requestStream))
                                requestWriter.Write(NoticeBuilder.ToJsonString(notice));

                        request.GetResponseAsync().ContinueWith(responseTask =>
                        {
                            if (responseTask.IsFaulted)
                            {
                                if (responseTask.Exception != null)
                                {
                                    tcs.SetException(responseTask.Exception.InnerExceptions);
                                }
                            }
                            else if (responseTask.IsCanceled)
                            {
                                tcs.SetCanceled();
                            }
                            else
                            {
                                IHttpResponse httpResponse = null;
                                try
                                {
                                    httpResponse = responseTask.Result;

                                    using (var responseStream = httpResponse.GetResponseStream())
                                        using (var responseReader = new StreamReader(responseStream))
                                        {
                                            var airbrakeResponse = JsonConvert.DeserializeObject <AirbrakeResponse>(responseReader.ReadToEnd());
                                            // Note: a success response means that the data has been received and accepted for processing.
                                            // Use the url or id in the response to query the status of an error. This will tell you if the error has been processed,
                                            // or if it has been rejected for reasons including invalid JSON and rate limiting.
                                            // If the request body size exceeds 64KB, the API will reject the notice and return a 413 Request Entity Too Large status.
                                            // TODO: Investigate response in case when request body size exceeds 64KB.
                                            airbrakeResponse.Status = httpResponse.StatusCode == HttpStatusCode.Created
                                            ? RequestStatus.Success
                                            : RequestStatus.RequestError;

                                            tcs.SetResult(airbrakeResponse);
                                        }
                                }
                                finally
                                {
                                    var disposableResponse = httpResponse as IDisposable;
                                    if (disposableResponse != null)
                                    {
                                        disposableResponse.Dispose();
                                    }
                                }
                            }
                        });
                    }
                });
            }
            catch (Exception ex)
            {
                tcs.SetException(ex);
                return(tcs.Task);
            }

            return(tcs.Task);
        }
        /// <summary>
        /// Notifies Airbrake on error in your app using asynchronous call.
        /// </summary>
#if NET35
        public void NotifyAsync(Exception exception, IHttpContext context = null)
        {
            if (string.IsNullOrEmpty(config.ProjectId))
            {
                throw new Exception("Project Id is required");
            }

            if (string.IsNullOrEmpty(config.ProjectKey))
            {
                throw new Exception("Project Key is required");
            }

            try
            {
                if (Utils.IsIgnoredEnvironment(config.Environment, config.IgnoreEnvironments))
                {
                    var response = new AirbrakeResponse {
                        Status = RequestStatus.Ignored
                    };

                    OnNotifyCompleted(new NotifyCompletedEventArgs(response, null, false, null));
                    return;
                }

                var noticeBuilder = new NoticeBuilder();
                noticeBuilder.SetErrorEntries(exception);
                noticeBuilder.SetConfigurationContext(config);

                if (context != null)
                {
                    noticeBuilder.SetHttpContext(context, config);
                }

                noticeBuilder.SetEnvironmentContext(Dns.GetHostName(), Environment.OSVersion.VersionString, "C#/NET35");

                var notice = noticeBuilder.ToNotice();

                if (filters.Count > 0)
                {
                    notice = Utils.ApplyFilters(notice, filters);
                }

                if (notice == null)
                {
                    var response = new AirbrakeResponse {
                        Status = RequestStatus.Ignored
                    };

                    OnNotifyCompleted(new NotifyCompletedEventArgs(response, null, false, null));
                    return;
                }

                var request = httpRequestHandler.Get();

                request.ContentType = "application/json";
                request.Accept      = "application/json";
                request.Method      = "POST";

                request.BeginGetRequestStream(requestStreamResult =>
                {
                    try
                    {
                        var req           = (IHttpRequest)requestStreamResult.AsyncState;
                        var requestStream = req.EndGetRequestStream(requestStreamResult);

                        using (var requestWriter = new StreamWriter(requestStream))
                            requestWriter.Write(NoticeBuilder.ToJsonString(notice));

                        req.BeginGetResponse(respRes =>
                        {
                            IHttpResponse httpResponse = null;
                            try
                            {
                                var req2     = (IHttpRequest)respRes.AsyncState;
                                httpResponse = req2.EndGetResponse(respRes);

                                using (var respStream = httpResponse.GetResponseStream())
                                    using (var responseReader = new StreamReader(respStream))
                                    {
                                        var airbrakeResponse    = JsonConvert.DeserializeObject <AirbrakeResponse>(responseReader.ReadToEnd());
                                        airbrakeResponse.Status = httpResponse.StatusCode == HttpStatusCode.Created
                                        ? RequestStatus.Success
                                        : RequestStatus.RequestError;

                                        OnNotifyCompleted(new NotifyCompletedEventArgs(airbrakeResponse, null, false, null));
                                    }
                            }
                            catch (Exception respException)
                            {
                                OnNotifyCompleted(new NotifyCompletedEventArgs(null, respException, false, null));
                            }
                            finally
                            {
                                var disposableResponse = httpResponse as IDisposable;
                                if (disposableResponse != null)
                                {
                                    disposableResponse.Dispose();
                                }
                            }
                        }, req);
                    }
                    catch (Exception reqException)
                    {
                        OnNotifyCompleted(new NotifyCompletedEventArgs(null, reqException, false, null));
                    }
                }, request);
            }
            catch (Exception ex)
            {
                OnNotifyCompleted(new NotifyCompletedEventArgs(null, ex, false, null));
            }
        }