Overview

The HTTP header of an object is a string sent by the server over HTTP protocol before it sends HTML data to browser. By modifying the HTTP header, you can change the response form of the page or communicate configuration information, such as modifying the caching time. Modifying an object's HTTP header does not modify the object itself.

For example, if the Content-Encoding in Header is modified to gzip, but the file itself has not been compressed to .gz file in advance, a decoding error will occur.

Note that archived objects do not support custom headers.

Directions

1. Log in to the COS Console, and then select the Bucket List in the left pane to go to the Bucket List page. Click the bucket of the object to enter the bucket.
   
2. Locate the object for which you want to set headers, and click Details on the right.
   
3. Go to the Custom Headers section, and click Add Header. Select a parameter type (enter custom content in the custom field), and enter a value. COS provides the following 6 HTTP headers for objects. Once the configuration is complete, click Save.

HTTP Header	Remarks	Example
Content-Type	MIME information of file	image/jpeg
Cache-Control	File caching mechanism	no-cache;max-age=200
Content-Disposition	Extension with a MIME type	attachment;filename="fname.ext"
Content-Encoding	File encoding format	UTF-8
Expires	Controls the expiration date of cache	Wed, 21 Oct 2015 07:28:00 GMT
x-cos-meta-[custom content]	Custom content	x-cos-meta-via: homepage

4. If you need to add custom headers for more than one object, you can select the objects, and click **Custom Header** under **More Actions**.

Samples

Under APPID 1250000000, a bucket named " example" is created. The object exampleobject.txt is uploaded under the bucket root directory.

If you do not customize the HTTP header for the object, the browser or client will get the following Object headers during download:

Request

GET /exampleobject.txt HTTP/1.1
Host: examplebucket-1250000000.file.myqcloud.com
Accept: */*

Response

HTTP/1.1 200 OK
Content-Language:zh-CN
Content-Type: text/plain
Content-Disposition: attachment; filename*="UTF-8''exampleobject.txt"
Access-Control-Allow-Origin: *
Last-Modified: Tue, 11 Jul 2017 15:30:35 GMT 

Add the following configurations:

When you send a request again, the browser or the client will get the following object headers:

Request

GET /exampleobject.txt HTTP/1.1
Host: examplebucket-1250000000.file.myqcloud.com
Accept: */*

Response

HTTP/1.1 200 OK
Content-Language:zh-CN
Cache-Control: no-cache
Content-Type: image/jpeg
Content-Disposition: attachment; filename*="abc.txt"
x-cos-meta-md5: 1234
Access-Control-Allow-Origin: *
Last-Modified: Tue, 11 Jul 2017 15:30:35 GMT