Updated on 2022-12-08 GMT+08:00

Making an API Request

This section describes the structure of a REST API, and uses the IAM API for obtaining a user token as an example to describe how to call an API. The obtained token is used to authenticate the calling of other APIs.

Request URI

A request URI is in the following format:

{URI-scheme}://{Endpoint}/{resource-path}?{query-string}

Table 1 Request URI

Parameter

Description

URI-scheme

Protocol used to transmit requests. All APIs use HTTPS.

Endpoint

Domain name or IP address of the server bearing the REST service endpoint. Obtain the value from Regions and Endpoints.

For example, the endpoint of IAM in the AP-Singapore region is iam.ap-southeast-3.myhuaweicloud.com.

resource-path

Access path of an API for performing a specified operation. Obtain the path from the URI of an API. For example, resource-path of the API used to obtain a user token is /v3/auth/tokens.

query-string

Query parameter, which is optional. Ensure that a question mark (?) is included before each query parameter that is in the format of "Parameter name=Parameter value". For example, ? limit=10 indicates that a maximum of 10 data records will be displayed.

For example, to obtain an IAM token in the AP-Singapore region, obtain the endpoint of IAM (iam.ap-southeast-3.myhuaweicloud.com) for this region and the resource-path (/v3/auth/tokens) in the URI of the API used to obtain a user token. Then, construct the URI as follows:

https://iam.ap-southeast-3.myhuaweicloud.com/v3/auth/tokens
Figure 1 Example URI

To simplify the URI display in this document, each API is provided only with a resource-path and a request method. The URI-scheme of all APIs is HTTPS, and the endpoints of all APIs in the same region are identical.

Request Method

The HTTP protocol defines the following request methods that can be used to send a request to the server.

Table 2 Request method

Request Method

Description

GET

Requests the server to return specified resources.

PUT

Requests the server to update specified resources.

POST

Requests the server to add a resource or perform special operations.

DELETE

Requests the server to delete a specified resource (for example, an object).

HEAD

Requests the server resource header.

PATCH

Requests the server to update partial content of a specified resource. If the resource does not exist, a new resource will be created.

For example, in the case of the API used to obtain a user token, the request method is POST. The request is as follows:

POST https://iam.ap-southeast-3.myhuaweicloud.com/v3/auth/tokens

Request Header

You can also add additional header fields to a request, such as the fields required by a specified URI or HTTP method. For example, to request authentication information, add Content-Type, which specifies the request body type.

Table 3 lists common request headers.

Table 3 Common request headers

Name

Description

Mandatory

Example

Content-Type

MIME type of the request body.

Yes

The default value is application/json. Other values will be described in the specific APIs.

Content-Length

Length of the request body. The unit is byte.

  • Optional for POST or PUT requests.
  • Must be left blank for GET requests.

3495

X-Auth-Token

User token. After the request is processed, the value of X-Subject-Token in the header is the token value.

No

NOTE:

Mandatory for token-based authentication.

MIIPAgYJKoZfegerIhvcNAQcCo...ggg1BBIINPXsidG9rZ

X-Language

Request language type.

Yes

en-us

For details about other headers, see the HTTP protocol.

The API used to obtain a user token does not require authentication. Therefore, only the Content-Type field needs to be added to requests for calling the API. An example of such requests is as follows:

POST https://iam.ap-southeast-3.myhuaweicloud.com/v3/auth/tokens  Content-Type: application/json

Request Body

The body of a request is often sent in a structured format as specified in the Content-Type header field. If the request body contains full-width characters, these characters must be coded in UTF-8.

The request body varies between APIs. Some APIs do not require the request body, such as the APIs requested using the GET and DELETE methods.

In the case of the API used to obtain a user token, the request parameters and parameter description can be obtained from the API request. The following provides an example request with a body included. Replace username, domainname, ******** (login password), and xxxxxxxxxx (project ID, for example, ap-southeast-3) with the actual values. To learn how to obtain a project ID, see Regions and Endpoints.

scope specifies where a token takes effect. In the example, the token takes effect only on the resources specified by the project ID. You can set scope to an account or a project under an account. For more information about this API, see Obtaining a User Token Through Password Authentication.

POST https://iam.ap-southeast-3.myhuaweicloud.com/v3/auth/tokens  
Content-Type: application/json  
{  
    "auth": {  
        "identity": {  
            "methods": [  
                "password"  
            ],  
            "password": {  
                "user": {  
                    "name": "username",  
                    "password": "********",  
                    "domain": {  
                        "name": "domainname"  
                    } 
                }  
            }  
        },  
        "scope": {  
            "project": {  
                "name": "xxxxxxxxxxxxxxxxxx"  
            }  
        }  
    }  
}

If all data required for the API request is available, you can send the request to call the API through curl, Postman, or coding. In the response to the API used to obtain a user token, x-subject-token is the desired user token. This token can then be used to authenticate the calling of other APIs.