Making an API Request
This section describes the structure of a REST API, and uses the IAM API for obtaining a user token as an example to describe how to call an API. The obtained token is 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 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 |
Specifies the domain name or IP address of the server bearing the REST service endpoint. Obtain the value from . |
resource-path |
API access path for performing a specified operation. Obtain the value from the URI of the API. For example, the resource-path of the API for obtaining a user token is /v3/auth/tokens. |
query-string |
Query parameter, which is optional. Not all APIs have a query parameter. Ensure that a question mark (?) is included before a query parameter that is in the format of "Parameter name=Parameter value". For example, ? limit=10 indicates that a maximum of 10 pieces of data is to be viewed. |
To simplify URI display, each API is provided with only 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 Methods
Method |
Description |
---|---|
GET |
Requests a server to return the specified resources. |
PUT |
Requests a server to update specified resources. |
POST |
Requests a server to add resources or perform special operations. |
DELETE |
Requests a server to delete specified resources, for example, an object. |
For example, in the URI for obtaining a user token, the request method is POST, and the request is as follows:
POST https://{{endpoint}}/v3/auth/tokens
Request Header
You can also add additional fields to a request, such as the fields required by a specified URI or an HTTP method. For example, add Content-Type that defines a request body type to request for the authentication information.
Name |
Description |
Mandatory |
Example |
---|---|---|---|
Content-Type |
Specifies the 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 can vary depending on the flow type. |
Yes |
application/json |
Content-Length |
Specifies the 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 |
Specifies the project ID. Obtain the project ID by following the instructions in Obtaining a Project ID. |
No |
e9993fc787d94b6c886cbaa340f9c0f4 |
X-Auth-Token |
Specifies the user token. After the request is processed, the value of X-Subject-Token in the header is the token value. |
Yes |
The following is part of an example token: MIIPAgYJKoZIhvcNAQcCo...ggg1BBIINPXsidG9rZ |
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://{{endpoint}}/v3/auth/tokens Content-Type: application/json
(Optional) Request Body
This part is optional. A request body is generally sent in a structured format (for example, JSON or XML), corresponding to Content-Type in the request header, and is used to transfer content other than the request header. If the request body contains Chinese characters, convert the Chinese characters into the UTF-8 encoding format.
The request body varies according to the APIs. Certain APIs do not require the request body, such as the GET and DELETE APIs.
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, domianname, ******** (login password), and xxxxxxxxxxxxxxxxxx (project name) with actual values. You can obtain the values from Regions and Endpoints.
scope specifies where a token takes effect. In the following example, the token takes effect only on the resources specified by the project ID. You can set the scope to an account or a project under an account. For details, see Obtaining a User Token.
POST https://{{endpoint}}/v3/auth/tokens Content-Type: application/json { "auth": { "identity": { "methods": [ "password" ], "password": { "user": { "name": "username", "password": "********", "domain": { "name": "domianname" } } } }, "scope": { "project": { "name": "xxxxxxxxxxxxxxxxxx" } } } }
If all data required by a request is available, you can send the request to call an 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.
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