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Updated on 2025-09-15 GMT+08:00
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Making an API Request

This section describes the structure of a RESTful API request, 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 the request header, most programming languages or frameworks require the request URI to be transmitted separately.

  • 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.myhwcloud.com.
  • resource-path: Access path of an API for performing a specified operation. Obtain the value from the URI of an API. For example, resource-path of the API for creating an IAM user is /v3.0/OS-USER/users.
  • query-string: Query parameter, which is optional. Ensure that a question mark (?) is included before the 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.myhwcloud.com) and resource-path (/v3.0/OS-USER/users) in the URI of the API for creating an IAM user as an administrator. 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:

  • 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 case of the API used to create 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.

Table 1 describes common request headers.

Table 1 Common request header fields

Parameter

Description

Mandatory

Example Value

Content-Type

Multipurpose Internet Mail Extensions (MIME) type of a request body. Its default value is application/json. Other values of this field will be provided for specific APIs if any.

Yes

application/json

X-Project-Id

Project ID. You can 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.

e9993fc787d**********aa340f9c0f4

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 a response is returned, 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

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

Request Body

The body of a request is often sent in a structured format 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.

For the API used to create an IAM user, you can check the required request parameters and their description in the API request. The following provides an example request with a body included. Replace the italic fields with the actual values.

  • accountid: ID of the account to which the IAM user belongs.
  • username: username of the IAM user to be created.
  • email: email address of the IAM user.
  • ********: login 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" 
     } 
 }

By now, all data required for an API request is available. You can send the request to call the API through curl, Postman, or coding.

Parent topic: Calling APIs