Making an API Request

Scenario

This section describes the structure of a REST API request, and uses the IAM API for obtaining a user token through password authentication as an example to demonstrate 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}

For example, to obtain an IAM token in the CN North-Beijing1 region, obtain the endpoint of IAM (iam.cn-north-1.myhuaweicloud.com) for this region and the resource-path (/v3/auth/tokens) in the URI of the API used to obtain a user token. Then, construct the URI as follows:

https://iam.ap-southeast-1.myhuaweicloud.com/v3/auth/tokens

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.

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.

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/auth/tokens

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.

Table 2 lists common request header fields.

In addition to supporting token-based authentication, Workspace APIs also support authentication using access key ID/secret access key (AK/SK). During AK/SK-based authentication, an SDK is used to sign the request, and the Authorization (signature information) and X-Sdk-Date (time when the request is sent) header fields are automatically added to the request.

For details, see "AK/SK-based Authentication" in AK/SK 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/auth/tokensContent-Type: application/json

(Optional) Request Body

The request body is optional. The body of a request is often 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, these characters must be encoded in UTF-8.

The request body varies depending on APIs. Certain APIs do not require a request body, such as the APIs requested using the GET and DELETE methods.

For the API used to obtain a user token, obtain the request parameters and parameter description in the API request. The following provides an example request with a body included. Replace username, domainname, ******** (login password), and xxxxxxxxxx (project ID) with the actual values. To learn how to obtain a project ID, see Regions and Endpoints.

The scope parameter specifies where a token takes effect. In the following example, the token takes effect only for the resources in a specified project. For more information about this API, see Obtaining a User Token Through Password Authentication.

POST https://iam.ap-southeast-1.myhuaweicloud.com/v3/auth/tokens 
Content-Type: application/json 
 
{ 
    "auth": { 
        "identity": { 
            "methods": [ 
                "password" 
            ], 
            "password": { 
                "user": { 
                    "name": "username", 
                    "password": "********", 
                    "domain": { 
                        "name": "domainname" 
                    } 
                } 
            } 
        }, 
        "scope": { 
            "project": { 
                "name": "xxxxxxxx" 
            } 
        } 
    } 
}

If all data required for the API request is available, you can send the request to call the API through curl, Postman, or coding. For the API used to obtain a user token, x-subject-token in the response header is the desired user token. Then, you can use the token to authenticate the calling of other APIs.