Making an API Request

Scenario

This section describes the structure of a REST API request, and uses the API for creating an IAM user as the administrator as an example to demonstrate how to call an API.

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.

• URI-scheme: protocol used to transmit requests. All APIs use HTTPS.
• Endpoint: domain name or IP address of the server running the REST service. The endpoint varies between services in different regions and 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 parameter, which is optional. Ensure there is a question mark (?) 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 displayed.

For example, if you want to create an IAM user, use the endpoint of any region (such as iam.ap-southeast-1.myhuaweicloud.com of CN-Hong Kong) because IAM is a global service. Then find the resource-path (/v3.0/OS-USER/users) in the URI of the API for creating an IAM user as the administrator, and assembly them as follows.

1

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

Figure 1 Example URI

To simplify the URI display, each API is provided only with a resource-path and a request method. This is because the URI-scheme value of all APIs is HTTPS, and the endpoints in a region are the same.

Request Method

HTTP defines the following request modes that can be used to send a request to the server:

• 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, to delete an object.
• HEAD: requests the server to return the response header only.
• PATCH: requests a server to update a part of a specified resource. If the resource is unavailable, the PATCH method is used to create a resource.

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 the authentication information, add Content-Type, which specifies the request body type.

Add the following common request header fields to a request:

• 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 authentication is enabled, this field is automatically specified when SDK is used to sign the request. For details, see AK/SK Authentication.
• X-Sdk-Date: time when a request is sent. This field is optional. When AK/SK authentication is enabled, this field is automatically specified when SDK is used to sign the request. For details, see AK/SK Authentication.
• X-Auth-Token: user token, which is optional. This field is mandatory for token 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. The X-Project-ID field is mandatory in the request header for accessing resources in a sub-project through AK/SK authentication.
• X-Domain-ID: account ID, which is optional. When you call APIs of global services using AK/SK authentication, X-Domain-ID is needed in the request header.

For the API used to create an IAM user as the administrator, if AK/SK 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

A request body is generally sent in a structured format as specified in Content-Type. The request body transfers content except the request header. If the request body contains Chinese characters, set Content-type to utf-8, for example, Content-Type: application/json; charset=utf-8.

The request body varies depending on APIs. Some APIs do not require the request body, such as the APIs requested using the GET or DELETE method.

For the API used to create an IAM user as the administrator, the required parameter and description are in the request part of the API. An example of such requests is as follows. Use actual values for the bold fields.

• accountid: account ID of the IAM user
• username: IAM username to be created
• email: email address of the 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. In the response to the API used to obtain a user token, x-subject-token is the desired user token. Then, you can use the token to authenticate the calling of other APIs.