Object Storage Service:Asynchronous processing (C# SDK V2)

Set up the client

using System.Text;
using OSS = AlibabaCloud.OSS.V2;  // Alias for the OSS SDK namespace.

var region = "cn-hangzhou";        // The region where the source bucket is located.
var endpoint = null as string;     // Optional. Overrides the default endpoint when set.
var bucket = "your bucket name";   // The source bucket name.
var key = "your object key";       // The object key of the document to transform.

// Load default SDK configuration and read credentials from environment variables
// (OSS_ACCESS_KEY_ID and OSS_ACCESS_KEY_SECRET).
var cfg = OSS.Configuration.LoadDefault();
cfg.CredentialsProvider = new OSS.Credentials.EnvironmentVariableCredentialsProvider();
cfg.Region = region;

if (endpoint != null)
{
    cfg.Endpoint = endpoint;
}

using var client = new OSS.Client(cfg);

Build the processing instruction

// Destination bucket and object key for the transformed output.
var targetBucket = bucket!;
var targetKey = $"process-{key}";  // Add a prefix to distinguish the output object.

// Transformation style: convert a Docx file to PNG.
// Format: doc/convert,target_{output_format},source_{input_format}
var style = "doc/convert,target_png,source_docx";

// Base64-encode the destination bucket name and object key.
var targetBucketBase64 = Convert.ToBase64String(Encoding.UTF8.GetBytes(targetBucket));
var targetKeyBase64    = Convert.ToBase64String(Encoding.UTF8.GetBytes(targetKey));

// Assemble the full processing instruction:
//   {style}|sys/saveas,b_{base64_bucket},o_{base64_key}/notify
//
//   sys/saveas  — saves the result to the specified destination.
//   b_...       — Base64-encoded destination bucket name.
//   o_...       — Base64-encoded destination object key.
//   /notify     — enables asynchronous processing mode.
var process = $"{style}|sys/saveas,b_{targetBucketBase64},o_{targetKeyBase64}/notify";

Call the API and handle the response

var result = await client.AsyncProcessObjectAsync(new OSS.Models.AsyncProcessObjectRequest
{
    Bucket  = bucket,
    Key     = key,
    Process = process
});

Console.WriteLine("AsyncProcessObject done");
Console.WriteLine($"Status code:    {result.StatusCode}");
Console.WriteLine($"Request ID:     {result.RequestId}");
Console.WriteLine($"Process result: {result.ProcessResult}");

Console.WriteLine("Response headers:");
result.Headers.ToList().ForEach(h => Console.WriteLine($"  {h.Key}: {h.Value}"));

Response fields