Making an API Request

Request URI

A request URI is in the following format:

{URI-scheme} :// {Endpoint} / {resource-path} ? {query-string}

Although a request URI is a part of a request header, most programming languages or frameworks require the request URI to be separately transmitted, rather than being conveyed in a request message.

For example, to obtain an IAM token 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/auth/tokens) in the URI of the API used to obtain a user token. Then, construct the URI as follows:

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

Request Method

For example, for the URI of the API used to obtain a user token, the request method is POST. The request is as follows:

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POST https://iam.cn-north-1.myhuaweicloud.com/v3/auth/tokens

Request Headers

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.

You can also add additional fields to the request header, for example, the fields required by a specified URI and an HTTP method. Table 3 lists common request header fields.

In addition to supporting token-based authentication, APIs 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 more information, see AK/SK-based Authentication.

(Optional) Request Body

This part is optional. 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. If the request body contains Chinese characters, these characters must be coded in UTF-8.

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

For the API used to obtain a user token, the request parameters and parameter description can be obtained in the API request. The following provides an example request with a body included. Replace username, domainname, ******** (login password), and xxxxxxxxxxxxxxxxxx (project name such as cn-north-1) with actual values. You can obtain the values from Regions and Endpoints.

The scope parameter specifies where a token takes effect. You can set scope to an account or a project under an account. In the following example, the token takes effect only for the resources in a specified project.

POST https://iam.cn-north-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": "xxxxxxxxxxxxxxxxxx"
            }
        }
    }
}

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 of obtaining a user token, x-subject-token in the response header is the required user token. This token can then be used to authenticate the calling of other APIs.

Initiating Requests

You can initiate a request based on the constructed request message in one of the following ways:

• cURL

  cURL is a command-line tool used to perform URL operations and transmit information. It serves as an HTTP client that can send HTTP requests to the server and receive response messages. cURL is used for API debugging. For more information about cURL, visit https://curl.haxx.se/.

  

  For security purposes, run the curl command on the server to query information, and then clear operation records, including but not limited to records in the ~/.bash_history and /var/log/messages directories (if any).

• Code

  You can call APIs using code to assemble, send, and process request messages.

• REST client

  Both Mozilla Firefox and Google Chrome provide a graphical browser plug-in, REST client, to send and process requests. For Mozilla Firefox, see Firefox REST Client. For Google Chrome, see Chrome REST Client.