ECS 3.6.2 Data Access Guide

Appending data to an object

You can use ECS extensions to the Swift protocol to append data to an object.

There may be cases where you need to append to an object, but determining the exact byte offset is not efficient or useful. For this scenario, ECS provides the ability to append data to the object without specifying an offset (the correct offset is returned to you in the response). For example, to append lines to a log file, on Swift or other Swift compatible platforms, you must send the full log file again.

A Range header with the special value bytes=-1- is used to append data to an object. In this way, the object is extended without knowing the existing object size. The format is: Range: bytes=-1-

A sample request showing appending to an existing object using a Range value of bytes=-1- is shown in the following example. Here the value and cat is sent in the request.

PUT /container1/object1 HTTP/1.1
Content-Length: 8
Range: bytes=-1-
ACCEPT: application/json,application/xml,text/html,application/octet-stream
Date: Mon, 12 Mar 2018 20:46:01 -0000
x-emc-namespace: emc
Content-Type: application/octet-stream
Authorization: AWS wuser1:/sqOFL65riEBSWLg6t8hL0DFW4c=
Accept-Encoding: gzip, deflate, compress
 
and cat
 
HTTP/1.1 204 No Content
ETag: 24
x-amz-id-2: object1
x-amz-request-id: 087ac237-6ff5-43e3-b587-0c8fe5c08732
Content-Length: 0
Date: Mon, 12 Mar 2018 20:46:01 GMT

When the object is retrieved, and cat is appended, and you see the full value: The quick green fox jumps over the lazy dog and cat.

GET /container1/object1 HTTP/1.1
ACCEPT: application/json,application/xml,text/html,application/octet-stream
Date: Mon, 12 Mar 2018 20:46:56 -0000
x-emc-namespace: emc
Content-Type: application/octet-stream
Authorization: AWS wuser1:D8FSE8JoLl0MTQcFmd4nG1gMDTg=
Accept-Encoding: gzip, deflate, compress
 
HTTP/1.1 200 OK
Date: Mon, 12 Mar 2018 20:46:56 GMT
Content-Type: application/octet-stream
Last-Modified: Mon, 12 Mar 2018 20:46:01 GMT
ETag: 24
Content-Type: application/json
Content-Length: 51
 
The quick green fox jumps over the lazy dog and cat.