Overview - Object Storage Service - Alibaba Cloud Documentation Center

If your business requires a high level of customization, you can directly call RESTful APIs. To directly call an API, you must include the signature calculation in your code. Object Storage Service (OSS) supports only virtual hosted-style URLs in RESTful API requests.

Format

All requests to OSS, except the GetService (ListBuckets) and DescribeRegions requests, include subdomain names. The subdomain names contain bucket information.

The domain name used to access a bucket is in the BucketName.Endpoint format. The BucketName parameter specifies the name of your bucket. The Endpoint parameter specifies the domain name used to access the region in which your bucket is located.

OSS endpoints include internal endpoints, public endpoints, and acceleration endpoints.

Note

OSS uses RESTful API operations to provide services. Different regions are accessed by using different endpoints. For more information, see Regions and endpoints.
You can use internal endpoints and public endpoints without additional configurations.
Before you use an acceleration endpoint, you must enable the transfer acceleration feature. For more information, see Enable transfer acceleration.
You can also replace a public endpoint with a custom domain name to access OSS resources. For more information, see Map custom domain names or Map an acceleration endpoint.

For example, the following endpoints are used to access buckets located in the China (Hangzhou) region:

Request style

For security reasons, you can use only virtual hosted-style URLs instead of path-style URLs when you initiate RESTful API requests. A virtual hosted-style URL contains the bucket name.

Format of virtual hosted-style URLs:

https://BucketName.Endpoint/objectName

Example of a virtual hosted-style URL:

https://examplebucket.oss-cn-hangzhou.aliyuncs.com/demo.png

Request header format

The following code shows the request header format of a RESTful API request that is sent to OSS:

GET / HTTP/1.1
Host: BucketName.Endpoint
Date: GMT Date
Authorization: SignatureValue

Header	Type	Description
Date	String	The GMT time specified in the HTTP/1.1 protocol. Example: Sun, 05 Sep 2021 23:00:00 GMT. This header is empty by default.
Host	String	The access domain name. Format: `BucketName.Endpoint`. This header is empty by default.
Authorization	String	The authentication information used to verify the validity of the request. This header is empty by default. Scenario: non-anonymous requests.

Sample requests

Sample request for a virtual hosted-style URL

Sample OSS resources:

Bucket name: examplebucket
Region: oss-cn-hangzhou
Object name: demo.png

Sample URL:

https://examplebucket.oss-cn-hangzhou.aliyuncs.com/demo.png

Sample requests:

GET /demo.png HTTP/1.1
Host: examplebucket.oss-cn-hangzhou.aliyuncs.com
Date: GMT Date
Authorization: SignatureValue

Sample request for a custom domain name

Sample custom domain name:

www.example.com

Sample OSS resources:

Bucket name: examplebucket
Object name: demo.png

Sample URL:

https://www.example.com/demo.png

Sample requests:

GET /demo.png HTTP/1.1
Host: example.com
Date: GMT Date
Authorization: SignatureValue

Signature methods

You can use one of the following methods to calculate signatures and add the signatures to the RESTful API requests:

Add signatures to request headers: In most cases, we recommend that you use this method. For more information, see Include signatures in the Authorization header.
Add signatures to URLs: If you use a signed URL to share data, the data can be obtained by all users over the Internet within the validity period of the signed URL. This causes security risks. If you want to provide a URL with signature information to a third-party user for authorized access, you can use this method. For more information, see Add signatures to URLs.

The following table describes the differences between the two signature methods.

Item	Add signatures to request headers	Add signatures to URLs
Configuration of the Expires parameter	No	Yes
Common request methods	GET, POST, PUT, and DELETE	GET and PUT
Time format	The Date request header is used to specify the request time in the GMT format. Important If the difference between the time specified by the Date header in a request and the time on the server when the request is received is greater than 15 minutes, OSS rejects the request and returns HTTP status code 403.	The Expires parameter is used to specify the time when the signed URL expires in the Unix timestamp format. Important If the time when OSS receives the URL request is later than the value of the Expires parameter that is included in the signature, a request timeout error is returned.
URL-encoded signatures	No	Yes

API operations

For more information about the API operations that are provided by OSS, see List of operations by function.