calling-cognitive-services.cs

    public static class CognitiveServicesFunction
    {

        private static string subscriptionKey = Environment.GetEnvironmentVariable("COMPUTER_VISION_SUBSCRIPTION_KEY");
        private static string endpoint = Environment.GetEnvironmentVariable("COMPUTER_VISION_ENDPOINT");
        private static string uriBase = endpoint + "vision/v2.1/analyze";

        [FunctionName("CognitiveServicesFunction")]
        public static async Task Run(
            [BlobTrigger("scaled-images/{name}", Connection = "")] CloudBlockBlob blob, 
            string name,
            ILogger log)
        {
            log.LogInformation($"Incoming scaled image, going to analyse it using cognitive services");
            try
            {
                var httpClient = new HttpClient();
                httpClient.DefaultRequestHeaders.Add("Ocp-Apim-Subscription-Key", subscriptionKey);

                await blob.FetchAttributesAsync();
                long fileByteLength = blob.Properties.Length;
                byte[] fileContent = new byte[fileByteLength];

                string uri = $"{uriBase}?visualFeatures=Categories,Description,Color";

                var downloaded = await blob.DownloadToByteArrayAsync(fileContent, 0);
                using (ByteArrayContent content = new ByteArrayContent(fileContent))
                {
                    content.Headers.ContentType =
                        new MediaTypeHeaderValue("application/octet-stream");
                    var response = await httpClient.PostAsync(uri, content);
                    string contentString = await response.Content.ReadAsStringAsync();
                    Console.WriteLine("\nResponse:\n\n{0}\n",
                        JToken.Parse(contentString).ToString());
                }
                await blob.DeleteIfExistsAsync();
            }
            catch (Exception e)
            {
                Console.WriteLine("\n" + e.Message);
            }
        }
    }