Performing an Appendable Upload

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The API append_object shares the same parameters and usage as that of put_object. The only difference is that the start position of the write object is added.

Parameter Description

Field	Type	Mandatory or Optional	Description
option	The context of the bucket. For details, see Configuring option.	Mandatory	Bucket parameter
key	char *	Mandatory	Object name
content_length	uint64_t	Mandatory	Length of the object content
position	char *	Mandatory	Start position of the appended write object
put_properties	obs_put_properties*	Mandatory	Properties of the uploaded object
encryption_params	server_side_encryption_params *	Optional	Encryption setting of the uploaded object
handler	obs_append_object_handler *	Mandatory	Callback function
callback_data	void *	Optional	Callback data

Sample Code

static void test_append_object_from_buffer()
{
    // Buffer to be uploaded
    char *buffer = "abcdefg";
    // Length of the buffer to be uploaded
    int buffer_size = strlen(buffer);
    // Name of an object to be uploaded
    char *key = "put_buffer_test";
    char * position = "0";
    // Initialize option.
    obs_options option;
    init_obs_options(&option);
    option.bucket_options.host_name = "<your-endpoint>";
    option.bucket_options.bucket_name = "<Your bucketname>";

    // 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 ACCESS_KEY_ID and SECRET_ACCESS_KEY.
    // 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.
    option.bucket_options.access_key = getenv("ACCESS_KEY_ID");
    option.bucket_options.secret_access_key = getenv("SECRET_ACCESS_KEY");
    option.bucket_options.certificate_info = "<Your certificate>";
    // Initialize the properties of an object to be uploaded.
    obs_put_properties put_properties;
    init_put_properties(&put_properties);
    // Initialize the structure for storing uploaded data.
    put_buffer_object_callback_data data;
    memset(&data, 0, sizeof(put_buffer_object_callback_data));
    // Assign the buffer value to the structure.
    data.put_buffer = buffer;
    // Set buffersize.
    data.buffer_size = buffer_size;
    // Set callback function.
    obs_append_object_handler putobjectHandler =
    { 
        { &response_properties_callback, &put_buffer_complete_callback },
          &put_buffer_data_callback
    };
    append_object(&option, key, buffer_size, position, &put_properties,
    0,&putobjectHandler,&data);
    if (OBS_STATUS_OK == data.ret_status) {
        printf("put object from buffer successfully. \n");
    }
    else
    {
        printf("put object from buffer failed(%s).\n", obs_get_status_name(data.ret_status));
    }
}

Objects uploaded using put_object, referred to as normal objects, can overwrite objects uploaded using append_object, referred to as appendable objects. Data cannot be appended to an appendable object anymore once the object has been overwritten by a normal object.
When you upload an object for the first time in appendable mode, an error will be reported (HTTP status code 409) if a common object with the same name is already present.
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 10,000 times of appendable uploads can be performed on a single object.
The sixth parameter in append_object is used to provide the server-side encryption. For details, see section Server-Side Encryption.