Completing a Multipart Upload

Function

After all parts are uploaded, you can call this API to assemble specified parts into an object.

Before performing this operation, you cannot download the uploaded data. When merging parts, you need to copy the additional message header information recorded during the initialization of the multipart upload task to the object metadata. The processing process is the same as that of the common upload object with these message headers. In the case of merging parts concurrently, the Last Write Win policy must be followed but the time for initiating Last Write is specified as the time when a part multipart upload is initiated.

As long as the multipart upload is not aborted, all uploaded parts occupy the space. However, after you assembled the specified parts, the uploaded but not assembled parts will be deleted to free up space.

You can send a request for downloading all or some data of the generated multipart by specifying a range.

You can send a request for deleting all parts uploaded in a multipart upload. Deleted data cannot be restored.

The merged parts do not use the MD5 value of the entire object as the ETag. Their ETag is calculated as follows: MD5(M₁M₂...M_N)-N, where M_n is the MD5 value of part n (N is the total number of parts). As described in the Sample Request, there are three parts and each part has an MD5 value. The MD5 values of the three parts are recalculated to obtain a new MD5 value. Then -N is added to the right of the MD5 value to get the ETag of the combined parts. In this example, -N is -3.

If the response to an object assembling request timed out and error 500 or 503 was returned, you can first obtain the object metadata of the multipart upload task. Then, check whether the value of header x-obs-uploadId in the response is the same as the ID of the current multipart upload task. If they are, it means the object parts have been successfully assembled on the server and you do not need to try again. For details, see Consistency of Concurrent Operations.

Working with Other Functions

Authorization

To call this API, you must be the bucket owner or have the permission to complete a multipart upload. You are advised to use IAM or bucket policies for authorization. For details about OBS authorization methods, see Differences Between OBS Permissions Control Methods.

• If you use IAM for authorization, you need to use either role/policy-based authorization or identity policy-based authorization and configure the required permissions:
  • If you use role/policy-based authorization (IAM v3 APIs in the old IAM version), you must have the obs:object:PutObject permission. For details, see Creating a Custom IAM Policy.
  • If you use identity policy-based authorization (IAM v5 APIs in the new IAM version), you must have the obs:object:putObject permission, as shown in the following table. For details, see Creating a Custom IAM Identity Policy.

    Action	Access Level	Resource Type (*: Required)	Condition Key	Alias	Dependencies
    obs:object:putObject	Permission_management	object *	g:EnterpriseProjectId	-	functiongraph:function:invokeAsync functiongraph:workflow:invoke smn:topic:publish
    		-	obs:EpochTime obs:SourceIp obs:TlsVersion obs:CustomDomain obs:x-obs-acl

• If you use bucket policies for authorization, you must have the obs:object:putObject permission. For details, see Creating a Custom Bucket Policy.

URI

POST /{object_key}

Calling Method

For details, see Calling APIs. Before calling this API, calculate the API signature and add it to the request.

You can debug this API in API Explorer.

Request Syntax

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POST /ObjectName?uploadId=uploadID HTTP/1.1 
Host: bucketname.obs.region.myhuaweicloud.com 
Date: date
Content-Length: length
Authorization: authorization
<CompleteMultipartUpload> 
    <Part> 
        <PartNumber>partNum</PartNumber> 
        <ETag>etag</ETag> 
    </Part> 
    <Part> 
        <PartNumber>partNum</PartNumber> 
        <ETag>etag</ETag> 
    </Part> 
    <Part> 
        <PartNumber>partNum</PartNumber> 
        <ETag>etag</ETag> 
    </Part> 
</CompleteMultipartUpload>

URI Parameters

This request uses parameters to specify the ID of a multipart upload whose parts will be assembled. Table 1 describes the parameters.

Request Headers

This request uses common headers. For details, see Table 3.

Request Body

This request uses elements to specify the list of parts to be assembled. Table 2 describes the elements.

Response Syntax

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HTTP/1.1 status_code
Date: date
<?xml version="1.0" encoding="UTF-8" standalone="yes"?> 
<CompleteMultipartUploadResult xmlns="http://obs.region.myhuaweicloud.com/doc/2015-06-30/">
    <Location>http://example-Bucket.obs.region.myhuaweicloud.com/example-Object</Location>
    <Bucket>bucketname</Bucket> 
    <Key>ObjectName</Key> 
    <ETag>ETag</ETag> 
</CompleteMultipartUploadResult>

Response Headers

This response uses common headers. For details, see Table 1.

In addition to the common response headers, the headers listed in Table 3 may be used.

Response Body

This response uses elements to return the result of assembling parts. Table 4 describes the elements.

Error Responses

1. If no message body exists, OBS returns 400 Bad Request.
2. If the message body format is incorrect, OBS returns 400 Bad Request.
3. If the part information in the message body is not sorted by part sequence number, OBS returns 400 Bad Request and the error code is InvalidPartOrder.
4. If the AK or signature is invalid, OBS returns 403 Forbidden and the error code is AccessDenied.
5. If the requested bucket is not found, OBS returns 404 Not Found and the error code is NoSuchBucket.
6. If the requested multipart upload does not exist, OBS returns 404 Not Found and error code NoSuchUpload.
7. If the user is not the initiator of the task, OBS returns 403 Forbidden and the error code is AccessDenied.
8. If the request part list contains a part that does not exist, OBS returns 400 Bad Request and the error code is InvalidPart.
9. If the part's ETag contained in the request list is incorrect, OBS returns 400 Bad Request with an error code of InvalidPart.
10. If the size of a part other than the last part is smaller than 100 KB, OBS returns 400 Bad Request.
11. If the size of the object is greater than 48.8 TB after parts being merged, OBS returns status code 400 Bad Request.

Other errors are included in Table 2.

Sample Request

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POST /object02?uploadId=00000163D46218698DF407362295674C HTTP/1.1
User-Agent: curl/7.29.0
Host: examplebucket.obs.region.myhuaweicloud.com
Accept: */*
Date: WED, 01 Jul 2015 05:23:46 GMT
Authorization: OBS H4IPJX0TQTHTHEBQQCEC:dOfK9iILcKxo58tRp3fWeDoYzKA=
Content-Length: 422

<?xml version="1.0" encoding="utf-8"?>
<CompleteMultipartUpload> 
  <Part> 
    <PartNumber>1</PartNumber>  
    <ETag>a54357aff0632cce46d942af68356b38</ETag> 
  </Part>  
  <Part> 
    <PartNumber>2</PartNumber>  
    <ETag>0c78aef83f66abc1fa1e8477f296d394</ETag> 
  </Part>  
  <Part> 
    <PartNumber>3</PartNumber>  
    <ETag>acbd18db4cc2f85cedef654fccc4a4d8</ETag> 
  </Part>
</CompleteMultipartUpload>

Sample Response

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HTTP/1.1 200 OK
Server: OBS
x-obs-request-id: 8DF400000163D4625BE3075019BD02B8
x-obs-id-2: 32AAAQAAEAABAAAQAAEAABAAAQAAEAABCSN8D1AfQcIvyGBZ9+Ee+jU6zv1iYdO4
Content-Type: application/xml
Date: WED, 01 Jul 2015 05:23:46 GMT
Content-Length: 326

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<CompleteMultipartUploadResult xmlns="http://obs.region.myhuaweicloud.com/doc/2015-06-30/">
    <Location>http://examplebucket.obs.region.myhuaweicloud.com/object02</Location>
    <Bucket>examplebucket</Bucket>
    <Key>object02</Key>
    <ETag>"03f814825e5a691489b947a2e120b2d3-3"</ETag>
</CompleteMultipartUploadResult>