Making an API Request

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

Request URI

A request URI consists of the following:

{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.

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 the CN-Hong Kong region is iam.ap-southeast-1.myhuaweicloud.com.
resource-path: API access path. Obtain the value from the URI of an API. For example, resource-path of the API used to create an IAM user as the administrator is /v3.0/OS-USER/users.
query-string: query parameters, which are optional. 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.

IAM is a global service. You can create an IAM user using the endpoint of IAM in any region. For example, to create an IAM user in the CN-Hong Kong region, obtain the endpoint of IAM (iam.ap-southeast-1.myhuaweicloud.com) for this region and resource-path (/v3.0/OS-USER/users) in the URI of the API for creating an IAM user. Then, construct the URI as follows:

https://iam.ap-southeast-1.myhuaweicloud.com/v3.0/OS-USER/users

Figure 1 Example URI

Click to enlarge

To simplify the URI display, 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 Methods

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

GET: requests the server to return specified resources.
PUT: requests the server to update specified resources.
POST: requests the server to add resources or perform special operations.
DELETE: requests the server to delete specified resources, for example, an object.

For example, in the case of the API for creating an IAM user, the request method is POST. An example request is as follows:

POST https://iam.ap-southeast-1.myhuaweicloud.com/v3.0/OS-USER/users

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, add Content-Type that defines a request body type to request for the authentication information.

Common request header fields are as follows:

Content-Type: request body type or format. This field is mandatory and its default value is application/json. Other values of this field will be provided for specific APIs if any.
Authorization: signature authentication information. This field is optional. When AK/SK-based authentication is enabled, this field is automatically specified when SDK is used to sign the request. For more information, see AK/SK-based Authentication.
X-Sdk-Date: time when a request is sent. This field is optional. When AK/SK-based authentication is enabled, this field is automatically specified when SDK is used to sign the request. For more information, see AK/SK-based Authentication.
X-Auth-Token: user token only for token-based API authentication. 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.
X-Project-ID: subproject ID. This field is optional and can be used in multi-project scenarios. It is mandatory in the request header for accessing resources in a subproject through AK/SK-based authentication.
X-Domain-ID: account ID. This field is optional. It is mandatory in the request header for calling APIs of global services through AK/SK-based authentication.

The API used to create an IAM user 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/v3.0/OS-USER/users
Content-Type: application/json
X-Sdk-Date: 20240416T095341Z
Authorization: SDK-HMAC-SHA256 Access=****************, SignedHeaders=content-type;host;x-sdk-date, Signature=****************

(Optional) Request Body

This part is optional. A request body is generally sent in a structured format (for example, JSON or XML), corresponding to Content-Type in the request header, and is used to transfer content other than the request header. If the request body contains full-width characters, these characters must be coded in UTF-8.

The request body varies according to the APIs. Certain APIs do not require the request body, such as the GET and DELETE APIs.

For the API used to create an IAM user, the request parameters and parameter description can be obtained from the API request. The following provides an example request with a body included.

accountid: account ID of an IAM user
username: name of an IAM user
email: email of an IAM user
**********: password of the IAM user

POST https://iam.ap-southeast-1.myhuaweicloud.com/v3.0/OS-USER/users
Content-Type: application/json
X-Sdk-Date: 20240416T095341Z
Authorization: SDK-HMAC-SHA256 Access=****************, SignedHeaders=content-type;host;x-sdk-date, Signature=****************

{
     "user": {
         "domain_id": "accountid",
         "name": "username",
         "password": "**********",
         "email": "email",
         "description": "IAM User Description"
     }
 }

If all data required for the API request is available, you can send the request to call the API through curl, Postman, or coding.

Parent topic: Calling APIs

Previous topic: Calling APIs

Next topic: Authentication