Making an API Request

This section describes the structure of a REST API request and uses the API for querying organization information as an example to demonstrate how to call an API. This API can be called by any account in an organization.

Request URI

A request URI is in the following format:

{URI-scheme} :// {Endpoint} / {resource-path} ? {query-string}

**Table 1** Parameter description
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. For example, the endpoint of Organizations is organizations.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 for querying organization information is /v1/organizations.
query-string	An optional query parameter. 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 queried.

For example, to query organization information, obtain the Organizations endpoint (organizations.myhuaweicloud.com) and the resource-path (/v1/organizations) in the URI of the API used to query organization information. Then, construct the URI as follows:

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 HTTP 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 the server to return the response header only.
PATCH: requests 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 query organization information, the request method is GET. The request is as follows:

GET  https://organizations.myhuaweicloud.com/v1/organizations

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.

Common request header fields are as follows:

Content-Type: specifies the type or format of the message body. This field is mandatory and its default value is application/json.
Authorization: specifies the signature information mandatory in the request. For details about AK/SK-based authentication, see AK/SK-based Authentication.
X-Sdk-Date: specifies the time when the request was sent, for example, 20221107T020014Z. This field is mandatory.
Host: specifies the host address, for example, organizations.myhuaweicloud.com. This field is mandatory.

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.

For example, the request for the API used to query organization information is as follows:

GET https://organizations.myhuaweicloud.com/v1/organizations
content-type: application/json
X-Sdk-Date: 20230330T021902Z 
host: organizations.myhuaweicloud.com
Authorization: SDK-HMAC-SHA256 Access=xxxxxxxxxxxxxxxxxxx, SignedHeaders=content-type;host;x-sdk-date, Signature=xxxxxxxxxxxxxxxxxxxx

(Optional) Request Body

The body of a request is often sent in a structured format 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.