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 demonstrate how to call an API. The obtained token can then be used to authenticate the calling of other APIs.

Figure 1 Example request
Click to enlarge

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 transmitted separately.

**Table 1** URI parameters
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 Regions and Endpoints.
resource-path	Resource path, that is, the API access path. Obtain the path from the URI of an API. For example, the resource-path of the CBS API used to obtain the list of questions is */v1/{project_id}/qabots/{qabot_id}/suggestions. {project_id}* indicates the project ID, which can be obtained by referring to Obtaining a Project ID. *{qabot_id}* indicates the Q&A bot ID, which can be obtained from the QABot console of CBS.
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. This parameter is not used.

For example, to obtain the list of questions in the CN-Hong Kong region, obtain the endpoint (cbs-ext.ap-southeast-1.myhuaweicloud.com) of this region and the resource-path (/v1/{project_id}/qabots/{qabot_id}/suggestions) in the URI of the API used to obtain the list of questions. Then, construct the URI as follows:

https://cbs-ext.ap-southeast-1.myhuaweicloud.com/v1/{project_id}/qabots/{qabot_id}/suggestions

Figure 2 Example URI
Click to enlarge

To simplify the URI display in this document, each API is provided only with a resource-path and a request method. The URI-scheme value 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:

**Table 2** HTTPS methods
Method	Description
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	same as GET except that the server must return only the response header.
PATCH	requests the server to update partial content of a specified resource. If the resource does not exist, a new resource will be created.

In the case of the API used to obtain the list of questions, the request method is POST. The request is as follows:

POST https://cbs-ext.ap-southeast-1.myhuaweicloud.com/v1/{project_id}/qabots/{qabot_id}/suggestions

Request Header

You can also add additional header fields to a request, such as the fields required by a specified URI or HTTP method. Table 3 describes common request headers. For details about the request authentication information, see Authentication.

**Table 3** Common request header fields
Parameter	Description	Mandatory	Example
Content-type	MIME type of the body in the request.	Yes	application/json
Content-Length	Length of the request body. The unit is byte.	This parameter is optional for POST or PUT requests, but not required for GET requests.	3495
X-Auth-Token	User token. It is used to obtain the permission to call APIs. For details about how to obtain the value, see Token Authentication.	Yes	MIINRwYJKoZIhvcNAQcCoIINODCCDTQCAQExDTALBglghkgBZQMEAgEwgguVBgkqhkiG...
X-Language	Request language type.	No. The default value is zh-cn.	en-us

In addition to supporting token-based authentication, public cloud APIs also 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 details, see AK/SK-based Authentication.

The API used to obtain the list of questions does not require authentication. Therefore, Content-Type and X-Auth-Token fields needs to be added to requests for calling the API. An example of such requests is as follows:

POST https://cbs-ext.ap-southeast-1.myhuaweicloud.com/v1/{project_id}/qabots/{qabot_id}/suggestions
Content-Type: application/json
X-Auth-Token: MIIaBgYJKoZIhvcNAQcC...

Request Body

A request body is generally sent in a structured format (for example, JSON or XML). It corresponds 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, these characters must be coded in UTF-8.

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.

For the API of obtaining the list of questions, obtain the request parameters and parameter description in the API request. The following provides an example request with a body included.

POST https://cbs-ext.ap-southeast-1.myhuaweicloud.com/v1/{project_id}/qabots/{qabot_id}/suggestions
Content-Type: application/json
X-Auth-Token: MIIaBgYJKoZIhvcNAQcC...
{
    "question":" Cloud desktop",
    "top":2
}

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 the list of questions, obtain the request parameters and parameter descriptions from the response message.

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