Some applications are using a monolithic pattern: only one handler function is used for many (if not all) API Gateways. That handler function then dispatches the call to sub-handler functions using switches based on the URLs. Ideally, in the modelization, each API Gateway should be linked to its dedicated sub-handler function. However, in our modelization, all API Gateways will be linked to the root handler function. 

      	static string bucketName = "S3WestAsieRegion";
        static string key = $"key-{Guid.NewGuid().ToString("n").Substring(0, 8)}";

        static void Main(string[] args)
        {            
            using (var s3 = new AmazonS3Client(RegionEndpoint.USWest2))
            {
                CreateBucket(s3);
				WriteObject(s3);
				...
			}
		}

        static void CreateBucket(IAmazonS3 s3)
        {
            Task<PutBucketResponse> res = s3.PutBucketAsync(new PutBucketRequest().WithBucketName(bucketName));
            Task.WaitAll(res);

            if (res.IsCompletedSuccessfully)
            {
                Console.WriteLine("New S3 bucket created: {0}", bucketName);
            }
        }

        static void WriteObject(IAmazonS3 s3)
        {
            // The api call used in this method equates to S3's Put api and is
            // suitable for smaller files. To upload larger files and entire
            // folder hierarchies, with automatic usage of S3's multi-part apis for
            // files over 5MB in size, consider using the TransferUtility class
            // in the Amazon.S3.Transfer namespace.
            // See https://docs.aws.amazon.com/AmazonS3/latest/dev/HLuploadFileDotNet.html.
            var ms = new MemoryStream(Encoding.UTF8.GetBytes("Test S3 data"));
            var req = new PutObjectRequest
            {
                BucketName = bucketName,
                Key = key,
                InputStream = ms
            };

            Task<PutObjectResponse> res = s3.PutObjectAsync(req);
            Task.WaitAll(res);

            if (res.IsCompletedSuccessfully)
            {
                Console.WriteLine("Created object '{0}' in bucket '{1}'", key, bucketName);
            }
        }