Updated on 2023-06-25 GMT+08:00

Making an API Request

This section describes the structure of a Representational State Transfer (REST) API request, and uses the Identity and Access Management (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.

  • 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 system administrator.
  • resource-path: Access path of an API for performing a specified operation. Obtain the value from the URI of an 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. 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.

To simplify the URI display in this document, each API is provided only with a resource-path and a request method. The URI-scheme of all APIs is HTTPS, and the endpoints of all APIs in the same region are identical.

Request Methods

The HTTPS protocol defines the following request methods that can be used to send a request to the server:

  • GET: requests the server to return specified resources.
  • PUT: requests the server to update specified resources.
  • POST: requests the server to add resources or perform special operations.
  • DELETE: requests the server to delete specified resources, for example, an object.
  • HEAD: requests a server resource header.
  • PATCH: requests the server to update partial content of a specified resource. If the resource does not exist, a new resource can be created using the PATCH method.

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.{Endpoint}/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 HTTPS method. For example, to request for the authentication information, add Content-Type, which specifies the request body type.

Common request header fields are as follows:

  • Content-Type: specifies the request body type or format. This field is mandatory and its default value is application/json. Other values of this field will be provided for specific APIs if any.
  • X-Auth-Token: specifies a user token only for token-based API authentication. 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.
  • X-Project-ID: specifies a subproject ID. This parameter is optional and can be used in multi-project scenarios.
  • X-Domain-ID: specifies an account ID.

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.{Endpoint}/v3/auth/tokens  
Content-Type: application/json

Request Body

A request body is generally sent in a structured format. It corresponds to Content-Type in the request header and 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 the body included. Replace username, domainname, ******** (login password), and xxxxxxxxxxxxxxxxxx (project name) with the actual values. To learn how to obtain a project ID, see the system administrator.

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.

POST https://iam.{Endpoint}/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 the calling of other APIs.