Object Storage Service:Upload callbacks (C# SDK V1)

Usage notes

• In this topic, the public endpoint of the China (Hangzhou) region is used. If you want to access OSS from other Alibaba Cloud services in the same region as OSS, use an internal endpoint. For more information about OSS regions and endpoints, see Regions and endpoints.

• In this topic, an OSSClient instance is created by using an OSS endpoint. If you want to create an OSSClient instance by using custom domain names or Security Token Service (STS), see Initialization.

Sample code

The following code provides an example of how to use upload callbacks:

using System;
using System.IO;
using System.Text;
using Aliyun.OSS;
using Aliyun.OSS.Common;
using Aliyun.OSS.Util;
namespace Callback
{
    class Program
    {
        static void Main(string[] args)
        {
            Program.PutObjectCallback();
            Console.ReadKey();
        }
        public static void PutObjectCallback()
        {
            // Obtain access credentials from environment variables. Before you run this sample code, make sure that the OSS_ACCESS_KEY_ID and OSS_ACCESS_KEY_SECRET environment variables are set.
            var accessKeyId = Environment.GetEnvironmentVariable("OSS_ACCESS_KEY_ID");
            var accessKeySecret = Environment.GetEnvironmentVariable("OSS_ACCESS_KEY_SECRET");
            // Specify the bucket name, such as examplebucket.
            var bucketName = "examplebucket";
            // Specify the full path of the object, such as exampledir/exampleobject.txt. The full path cannot contain the bucket name.
            var objectName = "exampledir/exampleobject.txt";
           // Specify the full path of the local file, such as D:\\localpath\\examplefile.txt. If you do not specify a local path, the file is uploaded from the default path of the project.
            var localFilename = "D:\\localpath\\examplefile.txt";
            // Set the callback server URL, such as https://example.com:23450.
            const string callbackUrl = "yourCallbackServerUrl";
            // Set the value of the request body for the callback.
            const string callbackBody = "bucket=${bucket}&object=${object}&etag=${etag}&size=${size}&mimeType=${mimeType}&" +
                                        "my_var1=${x:var1}&my_var2=${x:var2}";
            //  Specify the Endpoint of the region where the bucket is located. For example, if the bucket is in the China (Hangzhou) region, set the Endpoint to https://oss-cn-hangzhou.aliyuncs.com.
            const string endpoint = "https://oss-cn-hangzhou.aliyuncs.com";
            // Specify the region where the bucket is located. For example, if the bucket is in the China (Hangzhou) region, set the region to cn-hangzhou.
            const string region = "cn-hangzhou";
            // Create a ClientConfiguration instance and modify the default parameters as needed.
            var conf = new ClientConfiguration();
            // Set the signature version to V4.
            conf.SignatureVersion = SignatureVersion.V4;

            // Create an OssClient instance.
            var client = new OssClient(endpoint, accessKeyId, accessKeySecret, conf);
            client.SetRegion(region);
            try
            {
                string responseContent = "";
                var metadata = BuildCallbackMetadata(callbackUrl, callbackBody);
                using (var fs = File.Open(localFilename, FileMode.Open))
                {
                    var putObjectRequest = new PutObjectRequest(bucketName, objectName, fs, metadata);
                    var result = client.PutObject(putObjectRequest);
                    responseContent = GetCallbackResponse(result);
                }
                Console.WriteLine("Put object:{0} succeeded, callback response content:{1}", objectName, responseContent);
            }
            catch (OssException ex)
            {
                Console.WriteLine("Failed with error code: {0}; Error info: {1}. \nRequestID: {2}\tHostID: {3}",
                    ex.ErrorCode, ex.Message, ex.RequestId, ex.HostId);
            }
            catch (Exception ex)
            {
                Console.WriteLine("Failed with error info: {0}", ex.Message);
            }
        }
        // Configure the upload callback.
        private static ObjectMetadata BuildCallbackMetadata(string callbackUrl, string callbackBody)
        {
            string callbackHeaderBuilder = new CallbackHeaderBuilder(callbackUrl, callbackBody).Build();
            string CallbackVariableHeaderBuilder = new CallbackVariableHeaderBuilder().
                AddCallbackVariable("x:var1", "x:value1").AddCallbackVariable("x:var2", "x:value2").Build();
            var metadata = new ObjectMetadata();
            metadata.AddHeader(HttpHeaders.Callback, callbackHeaderBuilder);
            metadata.AddHeader(HttpHeaders.CallbackVar, CallbackVariableHeaderBuilder);
            return metadata;
        }
        // Read the message returned from the upload callback.
        private static string GetCallbackResponse(PutObjectResult putObjectResult)
        {
            string callbackResponse = null;
            using (var stream = putObjectResult.ResponseStream)
            {
                var buffer = new byte[4 * 1024];
                var bytesRead = stream.Read(buffer, 0, buffer.Length);
                callbackResponse = Encoding.Default.GetString(buffer, 0, bytesRead);
            }
            return callbackResponse;
        }
    }
}

References

• For the complete sample code for upload callbacks, see GitHub sample.

• For more information about the API operation for upload callbacks, see Callback.