Making an API Request
This section describes the structure of a REST API and how to call an API. Before calling an API, you need to obtain the user token using the IAM API.
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.
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 endpoint. The endpoint varies depending on the service and service region. Endpoint: Endpoint of the Objective-func function. For details, see Regions and Endpoints. For example, the endpoint of IAM in region CN-Hong Kong is ddm.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 obtain a user token is /v3/auth/tokens. |
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. |
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:
1
|
https://iam.ap-southeast-1.myhuaweicloud.com/v3/auth/tokens |
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. Therefore, the two parts are omitted.
Request Method
Method |
Description |
---|---|
GET |
Requests a server to return specified resources. |
PUT |
Requests a server to update specified resources. |
POST |
Requests the server to add a resource or perform special operations. |
DELETE |
Requests a server to delete specified resources, for example, an object. |
For example, for the URI of the API used to obtain a user token, the request method is POST. The request is as follows:
1
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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.
Field |
Description |
Mandatory |
Example |
---|---|---|---|
Host |
Requested server information, which can be obtained from the URL of the service API. The value is in the hostname[:port] format. If the port number is not specified, the default port is used. The default port number for https is 443. |
No This parameter is mandatory for AK/SK authentication. |
code.test.com or code.test.com:443 |
Content-Type |
MIME type of the request body. You are advised to use the default value application/json. For APIs used to upload objects or images, the value varies depending on the flow type. |
Yes |
application/json |
Content-Length |
Length of the request body. The unit is byte. |
This parameter is optional for POST requests, but must be left blank for GET requests. |
3495 |
X-Project-Id |
Project ID. Obtain the project ID by following the instructions in Obtaining a Project ID. |
No This parameter is mandatory for requests that use AK/SK authentication in the Dedicated Cloud (DeC) scenario or multi-project scenario. |
e9993fc787d94b6c886cbaa340f9c0f4 |
X-Auth-Token |
User token After the request is processed, the value of X-Subject-Token in the header is the token value. |
No This parameter is mandatory for token authentication. |
The following is part of an example token: MIIPAgYJKoZIhvcNAQcCo...ggg1BBIINPXsidG9rZ |
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.
The API used to obtain a user token does not require authentication. Therefore, this API only requires adding the Content-Type field. The request with the added Content-Type header is as follows:
POST https://iam.cn-north-1.myhuaweicloud.com/v3/auth/tokens Content-Type: application/json
(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.
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