public async Task CollectAsync(params Span[] spans)
        {
            var request = WebRequest.CreateHttp(_url);

            request.Method      = "POST";
            request.ContentType = "application/x-thrift";

            using (var output = new MemoryStream())
            {
                ThriftSpanSerializer.WriteSpans(spans, output);
                output.Position       = 0;
                request.ContentLength = output.Length;
                using (var stream = await request.GetRequestStreamAsync())
                {
                    await output.CopyToAsync(stream);

                    await stream.FlushAsync();
                }
            }

            using (var reply = (HttpWebResponse)await request.GetResponseAsync())
            {
                if (reply.StatusCode != HttpStatusCode.Accepted)
                {
                    throw new ZipkinCollectorException($"Zipkin HTTP receiver responded with status code {reply.StatusCode}");
                }
            }
        }
        public async Task CollectAsync(params Span[] spans)
        {
            using (var stream = new MemoryStream())
            {
                ThriftSpanSerializer.WriteSpans(spans, stream);
                stream.Position = 0;

                var message = new Message
                {
                    Value = stream.ToArray()
                };

                var result = await _producer.SendMessageAsync(_settings.ZipkinTopic, new[] { message });

                var res = result.First();
                if (res.Error != 0)
                {
                    throw new ZipkinCollectorException($"An error (code: {res.Error}) occurred while sending trace data to zipkin-kafka");
                }
            }
        }