Making an API Request
This section describes the structure of a REST API request, and uses the IAM API for obtaining a user token 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 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.
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 the administrator. |
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:
https://iam.ap-southeast-1.myhuaweicloud.com/v3/auth/tokens
![](https://support.huaweicloud.com/intl/en-us/api-koophone/en-us_image_0000001866822121.png)
![](https://support.huaweicloud.com/intl/en-us/api-koophone/public_sys-resources/note_3.0-en-us.png)
To simplify URI display, only the resource-path and request method are displayed. 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:
Method |
Description |
---|---|
GET |
Request the server to return specified resources. |
PUT |
Request the server to update specified resources. |
POST |
Request the server to add resources or perform special operations. |
DELETE |
Request the server to delete specified resources, for example, an object. |
HEAD |
Request the server to return only the response header. |
PATCH |
Request 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/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 for the authentication information, add Content-Type, which specifies the request body type.
Name |
Description |
Mandatory |
Example |
---|---|---|---|
Host |
Request server information, which is obtained from the URL of a service API. The value is in the format of hostname[:port]. If the port number is not specified, the default port 443 is used for HTTPS. |
No This field is mandatory for authentication using access key ID/secret access key (AK/SK). |
code.test.com or code.test.com:443 |
Content-Type |
Request body type or format. The default value application/json is recommended. Other values of this field will be provided for specific APIs if any. |
No |
application/json |
Content-Length |
Length of the request body, in bytes. |
No |
3495 |
X-Auth-Token |
User token. 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. The token is the value of X-Subject-Token in the response header. |
No This field is mandatory for token-based authentication. |
The following is part of an example token: MIIPAgYJKoZIhvcNAQcCo...ggg1BBIINPXsidG9rZ |
![](https://support.huaweicloud.com/intl/en-us/api-koophone/public_sys-resources/note_3.0-en-us.png)
In addition to supporting token-based authentication, APIs support authentication using 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" in 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:
1 2 |
POST https://iam.ap-southeast-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. The request body transfers content except the request header.
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 username, domainname, ******** (login password), and xxxxxxxxxxxxxxxxxx (project name) with the actual values. Obtain the project name from Regions and Endpoints.
![](https://support.huaweicloud.com/intl/en-us/api-koophone/public_sys-resources/note_3.0-en-us.png)
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. For more information about this API, see Obtaining a User Token.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 |
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": "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. 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 requests for calling other APIs.
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