Making an API Request

Updated on 2024-01-16 GMT+08:00

View PDF

This section describes the structure of a RESTful API request, and uses the IAM service as an example to explain how to obtain a user token to call an API. The obtained token can then be used to authenticate the calling of other APIs.

Request URI

The format of a request URI is as follows:

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

Although a request URI is included in the request header, most programming languages or frameworks require passing the request URI separately.

**Table 1** URI parameters
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. The endpoint varies between services in different regions. It can be obtained from Regions and Endpoints. For details about Message & SMS endpoints, see Obtaining an Endpoint.
resource-path	Resource path, that is, API access path. Obtain the path from the URI of an API. For example, the resource-path of the API for obtaining a user token is /v3/auth/tokens.
query-string	(Optional) Query parameter. Ensure that a question mark (?) is included in front of 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 queried.

For example, to obtain an IAM token in the CN-Hong Kong region, obtain the endpoint of IAM (iam.ap-southeast-1.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:

Figure 1 Example URI

NOTE:

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.

Method

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

**Table 2** HTTP methods
Method	Description
GET	Requests a server to return specified resources.
PUT	Requests a server to update specified resources.
POST	Requests a server to add resources or perform a special operation.
DELETE	Requests the server to delete specified resources, for example, an object.
HEAD	Requests a server for resource header.
PATCH	Requests a server to update part of specified resources. If the requested resource does not exist, the server may create a resource using the PATCH method.

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-1.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 for the authentication information, add Content-Type, which specifies the request body type.

For details about common request headers, see Table 1.

**Table 3** Common request header
Parameter	Description	Mandatory	Example
Host	Server information of the resource being requested. The value can be obtained from the URL of the service API. The value is in the format of Hostname:Port number. If the port number is not specified, the default port is used. The default port number for HTTPS is 443.	No This parameter is mandatory for AK/SK authentication.	code.test.com or code.test.com:443
Content-Type	Message body type or format. The default value application/json is recommended. Other values of this field will be provided for specific APIs if any.	Yes	application/json
Content-Length	Length of a request body, in bytes.	No	3495
X-Project-Id	Project ID. Obtain it by referring to Obtaining a Project ID.	No This field is mandatory for requests that use AK/SK authentication in the Dedicated Cloud (DeC) scenario or multi-project scenario.	e9993fc787d94b6c886cbaa340f9c0f4
X-Auth-Token	User token. The user token is a response to the API used to obtain a user token. This API is the only one that does not require authentication. After the request is processed, the value of X-Subject-Token in the response header is the token value.	No This parameter is mandatory for token authentication.	The following is part of an example token: MIIPAgYJKoZIhvcNAQcCo...ggg1BBIINPXsidG9rZ

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-1.myhuaweicloud.com/v3/auth/tokens 
Content-Type: application/json

(Optional) Request Body

The request body is optional. A request body is often sent in a structured format (for example, JSON or XML) as defined in the Content-Type header field. If the request body contains full-width characters, these characters must be coded in UTF-8.

Request bodies vary depending on APIs. Some APIs do not require a 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, ******** (login password), domainname (account name), and xxxxxxxxxxxxxxxxxx (project name, for example, ap-southeast-1) with the actual values. For details about how to obtain the values, see Obtaining Account, IAM User, Group, Project, Region, and Agency Information.

NOTE:

The scope parameter specifies where a token takes effect. You can set scope to an account or a project under an account. In the following example, the token takes effect only for the resources in a specified project. For details, see Obtaining a User Token.

POST https://iam.cn-north-1.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 an API through curl, Postman, or coding. In the response to the API used to obtain a user token, x-subject-token is the target user token. You can use this token to authenticate the calling of other APIs.

Parent topic: Calling APIs

Previous topic: Calling APIs

Next topic: Authentication