Performing an Appendable Upload

If you have any questions during the development, post them on the Issues page of GitHub. For details about parameters and usage of each API, see the API Reference.

Appendable upload allows you to upload an object in appendable mode and then append data to the object. You can call ObsClient.AppendObject to perform an appendable upload. Sample code is as follows:

// Initialize configuration parameters.
ObsConfig config = new ObsConfig();
config.Endpoint = "https://your-endpoint";
// Hard-coded or plaintext AK/SK are risky. For security purposes, encrypt your AK/SK and store them in the configuration file or environment variables. In this example, the AK/SK are stored in environment variables for identity authentication. Before running this example, configure environment variables AccessKeyID and SecretAccessKey.
// Obtain an AK/SK pair on the management console. For details, see https://support.huaweicloud.com/intl/en-us/usermanual-ca/ca_01_0003.html.
string accessKey= Environment.GetEnvironmentVariable("AccessKeyID", EnvironmentVariableTarget.Machine);
string secretKey= Environment.GetEnvironmentVariable("SecretAccessKey", EnvironmentVariableTarget.Machine);
// Create an instance of ObsClient.
ObsClient client = new ObsClient(accessKey, secretKey, config);
try
{
    // Upload an object in appendable mode.
    AppendObjectRequest request = new AppendObjectRequest();
    request.BucketName = "bucketname";
    request.ObjectKey = "objectkey";
    request.InputStream = new MemoryStream(Encoding.UTF8.GetBytes("Hello OBS"));

    AppendObjectResponse response = client.AppendObject(request);

    // Append data to the object.
    request.Position = response.NextPosition;
    request.InputStream = new MemoryStream(Encoding.UTF8.GetBytes("Hello OBS Again"));
    response = client.AppendObject(request);
    Console.WriteLine("NextPosition:{0}", response.NextPosition);
    Console.WriteLine("ETag:{0}", response.ETag);

    // Use the API for obtaining object properties to get the start position for next appending.
    GetObjectMetadataResponse metadataResponse = client.GetObjectMetadata("bucketname", "objectkey");
    Console.WriteLine("NextPosition from metadata:{0}", metadataResponse.NextPosition);

}
catch (ObsException ex)
{
    Console.WriteLine("ErrorCode: {0}", ex.ErrorCode);
    Console.WriteLine("ErrorMessage: {0}", ex.ErrorMessage);
}

• Objects uploaded using ObsClient.PutObject, referred to as normal objects, can overwrite objects uploaded using ObsClient.AppendObject, referred to as appendable objects. Data cannot be appended to an appendable object once the object has been overwritten by a normal object.
• When you upload an object for the first time in appendable mode, an exception will be thrown (status code 409) if a normal object with the same name exists.
• The ETag returned for each append upload is the ETag for the uploaded content, rather than that of the whole object.
• Data appended each time can be up to 5 GB, and 10000 times of appendable uploads can be performed on a single object.
• After an appendable upload is successful, you can use AppendObjectResponse.NextPosition or call ObsClient.GetObjectMetadata to get the start position for next appending.