Updated on 2025-10-31 GMT+08:00

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.

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 be transmitted separately, 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 where the REST service is deployed. The value varies depending on services and regions. CDN is a global-level service and region selection is not required. Obtain the endpoint from Regions and Endpoints.

For example, the endpoint of IAM in 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 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 create an IAM user, obtain the endpoint of any region (for example, the endpoint of CN-Hong Kong: iam.ap-southeast-1.myhuaweicloud.com) 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

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 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 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.

HEAD

Same as GET except that the server must return only the response 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 URI of the API for creating an IAM user, the request method is POST. The 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, to request for the authentication information, add Content-Type, which specifies the request body type.

Common request header fields are as follows:

  • Content-Type: specifies the 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: specifies the 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: specifies a 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: specifies a 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: specifies an account ID, which is optional. It is mandatory in the request header for calling APIs of global services through AK/SK-based authentication.

For the API for creating an IAM user, if AK/SK-based authentication is enabled, the request with the header 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=****************

Request Body

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.

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 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
  • **********: login password of an 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.