Updated on 2024-07-17 GMT+08:00

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 demonstrate 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.

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 to create an IAM user as the administrator is /v3.0/OS-USER/u.

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.

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 the resource-path (/v3.0/OS-USER/users) in the URI of the API used to create an IAM User as the administrator. Then, construct the URL 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 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/v3.0/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.
Table 3 Common request header fields

Parameter

Description

Content-Type

Type or format of the request body. 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. During AK/SK-based authentication, this field is automatically added in the request when SDKs are 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. During AK/SK-based authentication, this field is automatically added in the request when SDKs are used to sign the request. For more information, see AK/SK-based Authentication.

X-Auth-Token

User token. This field is mandatory only for token-based authentication.

It is a response to the API for obtaining a user token (This is the only API that does not require authentication).

X-Project-ID

Subproject ID. This parameter is mandatory only in multi-project scenarios. The X-Project-ID field is mandatory in the request header for accessing resources in a sub-project through AK/SK-based authentication.

X-Domain-ID

Account ID. The X-Domain-ID field is mandatory for calling APIs of global services through AK/SK-based authentication.

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/v3.0/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

The body of a request is often sent in a structured format (JSON or XML) as specified in the Content-Type header field. The request body transfers content except the request header. The request body can contain Chinese characters in the UTF-8 encoding format.

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 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 the fields in bold with the actual values.

  • 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
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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. 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.