ECS 3.6.2 Data Access Guide

Updating a byte range within an object

You can use ECS extensions to the S3 protocol to update a byte range within an object.

Partially updating an object can be very useful in many cases. For example, to modify a binary header that is stored at the beginning of a large file. On Amazon or other S3 compatible platforms, it is necessary to send the full file again.

The following example demonstrates use of the byte range update. In the example, object1 has the value The quick brown fox jumps over the lazy dog.

GET /bucket1/object1 HTTP/1.1
Date: Mon, 12 Mar 2018 20:04:40 -0000
x-emc-namespace: emc
Content-Type: application/octet-stream
Authorization: AWS wuser1:9qxKiHt2H7upUDPF86dvGp8VdvI=
Accept-Encoding: gzip, deflate, compress
 
HTTP/1.1 200 OK
Date: Mon, 12 Mar 2018 20:04:40 GMT
Content-Type: application/octet-stream
Last-Modified: Mon, 12 Mar 2018 20:04:28 GMT
ETag: 6
Content-Type: application/json
Content-Length: 43
 
The quick brown fox jumps over the lazy dog.

To update a specific byte range within this object, the Range header in the object data request must include the start and end offsets of the object that you want to update. 
The format is: Range: bytes=<startOffset>-<endOffset>.

In the example, the PUT request includes the Range header with the value bytes=10-14 indicating to replace the bytes 10,11,12,13,14 by the value that is sent in the request. Here, the new value green is being sent.

PUT /bucket1/object1 HTTP/1.1
Content-Length: 5
Range: bytes=10-14
ACCEPT: application/json,application/xml,text/html,application/octet-stream
Date: Mon, 12 Mar 2018 20:15:16 -0000
x-emc-namespace: emc
Content-Type: application/octet-stream
Authorization: AWS wuser1:xHJcAYAEQansKLaF+/4PdLBHyaM=
Accept-Encoding: gzip, deflate, compress
 
green
 
HTTP/1.1 204 No Content
ETag: 10
x-amz-id-2: object1
x-amz-request-id: 027f037c-29ea-4670-8670-de82d0e9f52a
Content-Length: 0
Date: Mon, 12 Mar 2018 20:15:16 GMT

When reading the object again, the new value is now The quick green fox jumps over the lazy dog. A specific byte range within the object is updated, replacing the word brown with the word green.

GET /bucket1/object1 HTTP/1.1
Cookie: JSESSIONID=wdit99359t8rnvipinz4tbtu
ACCEPT: application/json,application/xml,text/html,application/octet-stream
Date: Mon, 12 Mar 2018 20:16:00 -0000
x-emc-namespace: emc
Content-Type: application/octet-stream
Authorization: AWS wuser1:OGVN4z8NV5vnSAilQTdpv/fcQzU=
Accept-Encoding: gzip, deflate, compress
 
HTTP/1.1 200 OK
Date: Mon, 12 Mar 2018 20:16:00 GMT
Content-Type: application/octet-stream
Last-Modified: Mon, 12 Mar 2018 20:15:16 GMT
ETag: 10
Content-Type: application/json
Content-Length: 43
 
The quick green fox jumps over the lazy dog.