Updated on 2024-06-20 GMT+08:00

Making an API Request

This section describes the structure of a REST API request, and uses the IAM API for obtaining a user token as an example to demonstrate how to call an API. The obtained token can then be 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}

Although a request URI is included in a request header, most programming languages or frameworks require the request URI to be separately transmitted, rather than being conveyed in a request message.

Table 1 URI parameter description

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 example, the endpoint of IAM in region CN-Hong Kong is iam.ap-southeast-1.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, the resource-path of the API used for obtaining a user token is /v3/auth/tokens.

query-string

(Optional) Query parameter. Not all APIs have a query parameter. 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 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:

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https://iam.ap-southeast-1.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. This is because the URI-scheme of all APIs is HTTPS, and the endpoints in a region are the same.

Request Methods

The HTTP protocol 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 special operations.

DELETE

Requests the server to delete specified resources, for example, an object.

HEAD

Same as GET except that the server must return only the response header.

PATCH

Requests the server to update partial content of a resource.

If the requested resource does not exist, the server may create a resource using PATCH.

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-1.myhuaweicloud.com/v3/auth/tokens

Request Header

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

Common request header fields are as follows.
Table 3 Common request headers

Parameter

Description

Mandatory or Not

Example

Host

Request server information, which is obtained from the URL of a service API. This value is host name[:port number]. If the port number is not specified, the default port is used. The default port number for HTTPS is 443.

No

This field 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 the request body. The unit is byte.

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.

It is a response to the API for obtaining a user token (This is the only API 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 field is mandatory for token authentication.

The following is part of an example token:

MIIPAgYJKoZIhvcNAQcCo...ggg1BBIINPXsidG9rZ

In addition to supporting authentication using tokens, APIs support authentication using AK/SK, which uses SDKs to sign a request. During the signature, the Authorization (signature authentication) and X-Sdk-Date (time when a request is sent) headers are automatically added in the request.

For details, see "AK/SK Authentication" in Authentication.

The obtain a user token API only requires to add the Content-Type because authentication is not required, the request with the added header is as follows:

POST https://iam.ap-southeast-1.myhuaweicloud.com/v3/auth/tokens
Content-Type: application/json

(Optional) Request Body

This part is optional. The body of a request is often sent in a structured format (for example, JSON or XML) as specified in the Content-Type header field. The request body transfers content except the request header. 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.

For the obtain a user token API, the request parameters and parameter description are available in the request. The following provides an example request with a body included. Replace username, domainname, ******** (login password), and xxxxxxxxxxxxxxxxxx (project ID) with the actual values, for example, ap-southeast-1. Obtain the value from Regions and Endpoints.

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 more information about this API, see Obtaining a User Token.

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POST https://iam.ap-southeast-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"
            }
        }
    }
}

After all data required for the API request is available, 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.